feat: UX polish, localization, advert relocation, and map filter fixes

- i18n: translate connection screen + chat tab keys into 13 locales;
  add "Send my contact" (advert) strings in all locales
- feat: move self-advert from home header into composer "+" action menu
  (new lib/utils/advert_helper.dart, always shows Flood/Direct sheet)
- fix: hide-repeaters map toggle was bypassed in simple mode
- fix: simple mode map now shows only favourite chat contacts
- fix: wrap ListTiles in Material (contact_tile secondary actions,
  inferred contact group card) to satisfy Flutter ink assertions
- device-authoritative contact/channel sync and UX review fixes

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

lib/widgets/contacts/add_channel_dialog.dart

@@ -16,6 +16,7 @@ class _AddChannelSheetState extends State<AddChannelSheet> {
   final _nameController = TextEditingController();
   final _secretController = TextEditingController();
   bool _isCreating = false;
+  bool _obscureSecret = true;
 
   @override
   void dispose() {
@@ -203,8 +204,23 @@ class _AddChannelSheetState extends State<AddChannelSheet> {
                       labelText: l10n.channelSecret,
                       hintText: l10n.channelSecretHint,
                       border: const OutlineInputBorder(),
+                      suffixIcon: IconButton(
+                        onPressed: _isCreating
+                            ? null
+                            : () => setState(() {
+                                _obscureSecret = !_obscureSecret;
+                              }),
+                        icon: Icon(
+                          _obscureSecret
+                              ? Icons.visibility_outlined
+                              : Icons.visibility_off_outlined,
+                        ),
+                        tooltip: _obscureSecret
+                            ? 'Show secret'
+                            : 'Hide secret',
+                      ),
                     ),
-                    obscureText: true,
+                    obscureText: _obscureSecret,
                     enabled: !_isCreating,
                     maxLength: 32,
                     validator: _validateSecret,

lib/widgets/contacts/contact_tile.dart

@@ -120,34 +120,6 @@ class ContactTile extends StatelessWidget {
         : null;
     void handleTap() => _handlePrimaryTap(context, contact);
 
-    final onLongPress = isPingInProgress
-        ? null
-        : () async {
-            final connectionProvider = context.read<ConnectionProvider>();
-            final hasPath = contact.routeHasPath;
-
-            final result = await connectionProvider.smartPing(
-              contactPublicKey: contact.publicKey,
-              hasPath: hasPath,
-              onRetryWithFlooding: () {
-                if (context.mounted) {
-                  ToastLogger.warning(
-                    context,
-                    AppLocalizations.of(
-                      context,
-                    )!.directPingTimeout(contact.displayName),
-                  );
-                }
-              },
-            );
-
-            if (context.mounted && !result.success) {
-              ToastLogger.error(
-                context,
-                AppLocalizations.of(context)!.pingFailed(contact.displayName),
-              );
-            }
-          };
     final colorScheme = Theme.of(context).colorScheme;
     final titleStyle = Theme.of(context).textTheme.titleMedium?.copyWith(
       fontWeight: FontWeight.w800,
@@ -233,7 +205,7 @@ class ContactTile extends StatelessWidget {
         child: InkWell(
           borderRadius: BorderRadius.circular(18),
           onTap: handleTap,
-          onLongPress: onLongPress,
+          onLongPress: handleTap,
           child: Padding(
             padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 10),
             child: Row(
@@ -418,6 +390,36 @@ class ContactTile extends StatelessWidget {
     _showContactActionSheet(context, contact);
   }
 
+  Future<void> _smartPingContact(BuildContext context, Contact contact) async {
+    final connectionProvider = context.read<ConnectionProvider>();
+    final hasPath = contact.routeHasPath;
+
+    final result = await connectionProvider.smartPing(
+      contactPublicKey: contact.publicKey,
+      hasPath: hasPath,
+      onRetryWithFlooding: () {
+        if (context.mounted) {
+          ToastLogger.warning(
+            context,
+            AppLocalizations.of(
+              context,
+            )!.directPingTimeout(contact.displayName),
+          );
+        }
+      },
+    );
+
+    if (!context.mounted) return;
+    if (result.success) {
+      ToastLogger.success(context, 'Ping reply from ${contact.displayName}');
+    } else {
+      ToastLogger.error(
+        context,
+        AppLocalizations.of(context)!.pingFailed(contact.displayName),
+      );
+    }
+  }
+
   String _locationSharingErrorMessage(Object error) {
     final message = error.toString();
     if (message.startsWith('Bad state: ')) {
@@ -498,6 +500,11 @@ class ContactTile extends StatelessWidget {
         contact.type == ContactType.repeater ||
         contact.type == ContactType.sensor;
     final canPreviewSensor = contact.isSensor;
+    final canSmartPing =
+        contact.type == ContactType.chat || contact.type == ContactType.sensor;
+    final isPingInProgress = context.read<ConnectionProvider>().isPingInProgress(
+      contact.publicKey,
+    );
     final sensorsProvider = context.read<SensorsProvider>();
     final isInSensors = sensorsProvider.isWatched(contact.publicKeyHex);
     final channelLocationSharingFuture =
@@ -662,6 +669,16 @@ class ContactTile extends StatelessWidget {
                   _pingRelay(context, contact);
                 },
               ),
+            if (canSmartPing)
+              _ContactSheetAction(
+                icon: Icons.network_ping,
+                label: l10n.ping,
+                enabled: !isPingInProgress,
+                onTap: () async {
+                  Navigator.pop(context);
+                  await _smartPingContact(context, contact);
+                },
+              ),
             if (!contact.isPublicChannel)
               _ContactSheetAction(
                 icon: Icons.edit_outlined,
@@ -1596,11 +1613,12 @@ class _ContactActionSheetState extends State<_ContactActionSheet> {
                     ),
                   ),
                 ),
-                Container(
-                  decoration: BoxDecoration(
-                    color: colorScheme.surfaceContainerLow,
+                Material(
+                  color: colorScheme.surfaceContainerLow,
+                  clipBehavior: Clip.antiAlias,
+                  shape: RoundedRectangleBorder(
                     borderRadius: BorderRadius.circular(24),
-                    border: Border.all(
+                    side: BorderSide(
                       color: colorScheme.outlineVariant.withValues(alpha: 0.28),
                     ),
                   ),

lib/widgets/contacts/room_login_sheet.dart

@@ -21,7 +21,6 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
   final FocusNode _focusNode = FocusNode();
   bool _isLoggingIn = false;
   bool _obscurePassword = true;
-  bool _isDisposed = false; // Track disposal state for async callbacks
 
   @override
   void initState() {
@@ -31,7 +30,6 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
 
   @override
   void dispose() {
-    _isDisposed = true;
     _passwordController.dispose();
     _focusNode.dispose();
     super.dispose();
@@ -228,6 +226,15 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
     // Save password before sending
     await _savePassword(password);
 
+    if (!mounted) return;
+
+    // Capture references before the sheet pops: the login result arrives
+    // after Navigator.pop, when this State is disposed, so the callbacks
+    // below must not depend on this widget's context.
+    final messenger = ScaffoldMessenger.of(context);
+    final colorScheme = Theme.of(context).colorScheme;
+    final l10n = AppLocalizations.of(context)!;
+
     // Set up login callbacks
     Function(Uint8List, int, bool, int)? originalOnSuccess;
     Function(Uint8List)? originalOnFail;
@@ -251,12 +258,12 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
         '   Messages will be fetched when onMessageWaiting callback is triggered',
       );
 
-      // Check both _isDisposed flag and mounted to handle race conditions
-      if (_isDisposed || !mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
+      // Use the captured messenger: the sheet has already been popped by the
+      // time this callback fires, so this State's context is gone.
+      messenger.showSnackBar(
         SnackBar(
-          content: Text(AppLocalizations.of(context)!.loggedInSuccessfully),
-          backgroundColor: Theme.of(context).colorScheme.primary,
+          content: Text(l10n.loggedInSuccessfully),
+          backgroundColor: colorScheme.primary,
           duration: const Duration(seconds: 3),
         ),
       );
@@ -269,12 +276,12 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
 
       debugPrint('❌ [RoomLogin] Login failed - incorrect password');
 
-      // Check both _isDisposed flag and mounted to handle race conditions
-      if (_isDisposed || !mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
+      // Use the captured messenger: the sheet has already been popped by the
+      // time this callback fires, so this State's context is gone.
+      messenger.showSnackBar(
         SnackBar(
-          content: Text(AppLocalizations.of(context)!.loginFailed),
-          backgroundColor: Theme.of(context).colorScheme.error,
+          content: Text(l10n.loginFailed),
+          backgroundColor: colorScheme.error,
           duration: const Duration(seconds: 3),
         ),
       );
@@ -289,15 +296,14 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
 
       _focusNode.unfocus();
 
-      if (!mounted) return;
-      Navigator.pop(context); // Close the dialog
+      if (mounted) {
+        Navigator.pop(context); // Close the dialog
+      }
 
-      ScaffoldMessenger.of(context).showSnackBar(
+      messenger.showSnackBar(
         SnackBar(
-          content: Text(
-            AppLocalizations.of(context)!.loggingIn(widget.contact.displayName),
-          ),
-          backgroundColor: Theme.of(context).colorScheme.primary,
+          content: Text(l10n.loggingIn(widget.contact.displayName)),
+          backgroundColor: colorScheme.primary,
           duration: const Duration(seconds: 2),
         ),
       );
@@ -306,13 +312,10 @@ class _RoomLoginSheetState extends State<RoomLoginSheet> {
       connectionProvider.onLoginSuccess = originalOnSuccess;
       connectionProvider.onLoginFail = originalOnFail;
 
-      if (!mounted) return;
-      ScaffoldMessenger.of(context).showSnackBar(
+      messenger.showSnackBar(
         SnackBar(
-          content: Text(
-            AppLocalizations.of(context)!.failedToSendLogin(e.toString()),
-          ),
-          backgroundColor: Theme.of(context).colorScheme.error,
+          content: Text(l10n.failedToSendLogin(e.toString())),
+          backgroundColor: colorScheme.error,
         ),
       );
     } finally {