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/fireMarker.dart

@@ -11,10 +11,6 @@ Marker FireMarker(
   FireMarkType type, [
   VoidCallback? onTap,
 ]) {
-  // Calculate offset based on marker type
-  // Anchor point for center of marker: (40, calculated_y)
-  final Offset offset = _getAnchorOffset(type);
-
   return Marker(
     point: pos,
     width: 80.0,
@@ -26,21 +22,3 @@ Marker FireMarker(
     ),
   );
 }
-
-/// Get the anchor offset based on marker type
-Offset _getAnchorOffset(FireMarkType type) {
-  switch (type) {
-    case FireMarkType.position:
-      return const Offset(40.0, 20.0);
-    case FireMarkType.fire:
-      return const Offset(40.0, 24.0);
-    case FireMarkType.pixel:
-      // Auto-calculate based on marker size
-      return const Offset(40.0, 40.0);
-    case FireMarkType.falsePos:
-    case FireMarkType.industry:
-      return const Offset(40.0, 35.0);
-    default:
-      return const Offset(40.0, 40.0);
-  }
-}