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/fireMarkerIcon.dart

@@ -4,24 +4,19 @@ import 'colors.dart';
 import 'fireMarkType.dart';
 
 class FireMarkerIcon extends StatelessWidget {
-
   const FireMarkerIcon(this.type, {super.key});
   final FireMarkType type;
 
   @override
   Widget build(BuildContext context) {
-    switch (type) {
-      case FireMarkType.position:
-        return const Icon(Icons.location_on, color: fires600, size: 50.0);
-      case FireMarkType.pixel:
-        return const Icon(Icons.brightness_1, color: fires900, size: 3.0);
-      case FireMarkType.fire:
-        return Image.asset('images/fire-marker-l.png');
-      case FireMarkType.industry:
-        return Image.asset('images/industry-marker-reg.png');
-      case FireMarkType.falsePos:
-      default:
-        return Image.asset('images/industry-marker.png');
-    }
+    return switch (type) {
+      FireMarkType.position =>
+        const Icon(Icons.location_on, color: fires600, size: 50.0),
+      FireMarkType.pixel =>
+        const Icon(Icons.brightness_1, color: fires900, size: 3.0),
+      FireMarkType.fire => Image.asset('images/fire-marker-l.png'),
+      FireMarkType.industry => Image.asset('images/industry-marker-reg.png'),
+      FireMarkType.falsePos => Image.asset('images/industry-marker.png'),
+    };
   }
 }