chore(git): protect secrets and exclude generated files

- Ignore app_constants.dart to prevent API keys from being pushed
- Ignore .claude/ directory (AI assistant internal state)
- Existing *.g.dart and l10n generated file rules now enforced
  after removing previously tracked generated files

Author: Fury3K

.gitignore

@@ -33,6 +33,7 @@ offline_maps/
 
 # Secrets and Environment files
 lib/config/api_keys.dart
+lib/src/core/constants/app_constants.dart
 .env
 .env.*
 !.env.example
@@ -70,6 +71,9 @@ android/app/google-services.json
 **/ios/Runner/GeneratedPluginRegistrant.*
 ios/Runner/GoogleService-Info.plist
 
+# Claude Code
+.claude/
+
 # Miscellaneous
 *.class
 *.log