feat: Add setting to disable map tab for battery savings

Add a new "Disable Map" toggle in settings that allows users to hide
the map tab entirely. This is useful for scenarios where the map is
not needed and battery conservation is a priority.

Changes:
- Add disableMap and disableMapDescription localized strings (all languages)
- Add isMapEnabled state to AppProvider with persistence
- Update HomeScreen to dynamically adjust tab count based on setting
- Make onNavigateToMap optional in MessagesTab and ContactsTab
- Add toggle switch in Settings screen under Interface section

lib/screens/settings_screen.dart

@@ -528,6 +528,19 @@ class _SettingsScreenState extends State<SettingsScreen> {
               },
             ),
           ),
+          Consumer<AppProvider>(
+            builder: (context, appProvider, child) => SwitchListTile(
+              secondary: const Icon(Icons.map_outlined),
+              title: Text(AppLocalizations.of(context)!.disableMap),
+              subtitle: Text(
+                AppLocalizations.of(context)!.disableMapDescription,
+              ),
+              value: !appProvider.isMapEnabled,
+              onChanged: (value) async {
+                await appProvider.toggleMapEnabled(!value);
+              },
+            ),
+          ),
           ListTile(
             leading: const Icon(Icons.language),
             title: Text(AppLocalizations.of(context)!.language),