refactor: clean up 55 lint warnings and issues

- Remove all 31 avoid_print debug statements across codebase
- Fix 8 critical warnings (unused variables, unreachable defaults, etc)
- Update deprecated APIs: launch() → launchUrl(), textScaleFactor → textScaler
- Replace deprecated surfaceVariant → surfaceContainerHighest in Material 3 themes
- Refactor switch statements to use modern pattern matching
- Remove unused code: _showDialog, _initNoLocation, _getAnchorOffset
- Fix use_build_context_synchronously by adding mounted checks
- Add ignore_for_file annotations to generated JSON serialization files
- Fix type annotations in appState.dart and models

Warnings reduced from 301 to 246 issues (8 → 0 critical warnings).
Build verified: app-production-debug.apk (160MB) compiles successfully.
Zero type errors, Dart analysis clean for critical issues.

lib/models/fireNotification.g.dart

@@ -6,7 +6,7 @@ part of 'fireNotification.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
-FireNotification _$FireNotificationFromJson(Map<dynamic,dynamic> json) => $checkedCreate(
+FireNotification _$FireNotificationFromJson(Map json) => $checkedCreate(
       'FireNotification',
       json,
       ($checkedConvert) {