feat: Enhance contact telemetry updates with last seen timestamp and improve message bubble UI for SAR and drawing indicators

lib/providers/contacts_provider.dart

@@ -304,10 +304,19 @@ class ContactsProvider with ChangeNotifier {
       debugPrint('  ✅ Parsed new telemetry');
       debugPrint('  New telemetry timestamp: ${telemetry.timestamp}');
 
-      // Update contact with new telemetry
+      // Update contact with new telemetry AND last seen time
-      final updatedContact = contact.copyWith(telemetry: telemetry);
+      // lastAdvert is Unix timestamp in seconds
+      final currentTimestamp =
+          (DateTime.now().millisecondsSinceEpoch / 1000).round();
+      debugPrint('  Old lastAdvert: ${contact.lastAdvert}');
+      debugPrint('  New lastAdvert: $currentTimestamp');
+
+      final updatedContact = contact.copyWith(
+        telemetry: telemetry,
+        lastAdvert: currentTimestamp, // Update last seen time
+      );
       _contacts[contact.publicKeyHex] = updatedContact;
-      debugPrint('  ✅ Updated contact in map');
+      debugPrint('  ✅ Updated contact in map (with new lastAdvert)');
 
       _persistContacts();
       debugPrint('  ✅ Persisted contacts to storage');

lib/screens/messages_tab.dart

@@ -1413,7 +1413,8 @@ class _MessageBubble extends StatelessWidget {
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            // Header: Sender and time
+            // Header: Badge (if SAR or drawing) and time
+            if (isSarMarker || message.isDrawing)
               Row(
                 children: [
                   // Unread indicator badge
@@ -1491,8 +1492,37 @@ class _MessageBubble extends StatelessWidget {
                           ),
                         ],
                       ),
-                  )
+                    ),
-                else ...[
+                  const Spacer(),
+                  Text(
+                    message.getLocalizedTimeAgo(context),
+                    style: Theme.of(context).textTheme.labelSmall?.copyWith(
+                      fontWeight: isSarMarker
+                          ? FontWeight.w600
+                          : FontWeight.normal,
+                    ),
+                  ),
+                ],
+              ),
+
+            // Sender info row (shown for all messages)
+            Row(
+              children: [
+                // Unread indicator badge (only for regular messages, not SAR/drawing)
+                if (!message.isRead &&
+                    !message.isSentMessage &&
+                    !message.isSystemMessage &&
+                    !isSarMarker &&
+                    !message.isDrawing)
+                  Container(
+                    width: 8,
+                    height: 8,
+                    margin: const EdgeInsets.only(right: 8),
+                    decoration: const BoxDecoration(
+                      color: Colors.blue,
+                      shape: BoxShape.circle,
+                    ),
+                  ),
                 if (isOwnMessage)
                   Icon(
                     Icons.account_circle,
@@ -1536,15 +1566,12 @@ class _MessageBubble extends StatelessWidget {
                     ),
                   ),
                 ],
-                ],
                 const Spacer(),
+                // Time for regular messages (not shown for SAR/drawing as it's already above)
+                if (!isSarMarker && !message.isDrawing)
                   Text(
                     message.getLocalizedTimeAgo(context),
-                  style: Theme.of(context).textTheme.labelSmall?.copyWith(
+                    style: Theme.of(context).textTheme.labelSmall,
-                    fontWeight: isSarMarker
-                        ? FontWeight.w600
-                        : FontWeight.normal,
-                  ),
                   ),
               ],
             ),
@@ -1663,14 +1690,6 @@ class _MessageBubble extends StatelessWidget {
                                 ),
                               ],
                             ),
-                            if (drawing.senderName != null) ...[
-                              const SizedBox(height: 4),
-                              Text(
-                                'From: ${drawing.senderName}',
-                                style: Theme.of(context).textTheme.labelSmall
-                                    ?.copyWith(fontStyle: FontStyle.italic),
-                              ),
-                            ],
                           ],
                         ),
                       ),

test/services/cayenne_lpp_parser_test.dart

@@ -148,16 +148,16 @@ void main() {
 
       // Verify 3-byte signed encoding
       // Lat: -33.8688 * 10000 = -338688
-      // In 24-bit two's complement: -338688 + 0x1000000 = 16438608 = 0xFAD4E0
+      // In 24-bit two's complement: -338688 + 0x1000000 = 16438528 = 0xFAD500
       final latEncoded =
           (encoded[2] << 16) | (encoded[3] << 8) | encoded[4];
       // Lon: -151.2093 * 10000 = -1512093
-      // In 24-bit two's complement: -1512093 + 0x1000000 = 15265123 = 0xE8E963
+      // In 24-bit two's complement: -1512093 + 0x1000000 = 15265123 = 0xE8ED63
       final lonEncoded =
           (encoded[5] << 16) | (encoded[6] << 8) | encoded[7];
 
-      expect(latEncoded, equals(0xFAD4E0)); // Verify two's complement
+      expect(latEncoded, equals(0xFAD500)); // Verify two's complement
-      expect(lonEncoded, equals(0xE8E963));
+      expect(lonEncoded, equals(0xE8ED63));
 
       // Verify decoding
       final decoded = CayenneLppParser.parse(encoded);