feat: Enhance Dungeon Rendering with Size Adjustments and Testing Initialization

- Added InitializeForTesting method in Rom class to facilitate testing setup.
- Updated DungeonCanvasViewer to adjust object and sprite sizes from 16x16 to 8x8, improving rendering accuracy.
- Modified rendering logic for various dungeon objects (chests, doors, walls, pots) to reflect new size calculations.
- Adjusted object position calculations in ObjectRenderer to align with the new size metrics, ensuring consistent rendering across the application.
- Updated integration tests to verify the new initialization method for ROM objects.

src/app/rom.h

@@ -88,6 +88,11 @@ class Rom {
   absl::Status LoadZelda3(const RomLoadOptions& options);
   absl::Status LoadGfxGroups();
 
+  absl::Status InitializeForTesting() {
+    RETURN_IF_ERROR(LoadZelda3(RomLoadOptions::AppDefaults()));
+    return absl::OkStatus();
+  }
+
   absl::Status SaveGfxGroups();
   absl::Status SaveToFile(const SaveSettings& settings);
   absl::Status SavePalette(int index, const std::string& group_name,