feat: Enhance SAR message handling with color indexing and localization

- Added `sarColorIndex` to `Message` and `SarMarker` models to support color indexing for SAR markers.
- Introduced a standard color palette in `SarTemplate` and methods to retrieve colors based on index.
- Updated `SarTemplate` to include localization for template names.
- Modified `SarUpdateSheet` and message sending logic to include color index in SAR messages.
- Enhanced `SarMessageParser` to support both old and new message formats with color index.
- Updated UI components to reflect changes in SAR marker color handling based on the new color index.
- Improved sample data generation to utilize localized strings for better testing and demonstration.

lib/screens/settings_screen.dart

@@ -178,15 +178,20 @@ class _SettingsScreenState extends State<SettingsScreen> {
 
       if (!mounted) return;
 
+      // Get localization
+      final l10n = AppLocalizations.of(context)!;
+
       // Generate sample data
       final contacts = SampleDataGenerator.generateContacts(
         centerLocation: centerLocation,
+        l10n: l10n,
         teamMemberCount: 5,
         channelCount: 2,
       );
 
       final sarMessages = SampleDataGenerator.generateSarMarkerMessages(
         centerLocation: centerLocation,
+        l10n: l10n,
         foundPersonCount: 2,
         fireCount: 1,
         stagingCount: 1,
@@ -195,6 +200,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
 
       final channelMessages = SampleDataGenerator.generateChannelMessages(
         centerLocation: centerLocation,
+        l10n: l10n,
         generalChannelMessages: 8,
         emergencyChannelMessages: 5,
       );