feat(editor): implement overworld map editing features in ScreenEditor

- Added functionality for managing the overworld map, including loading, rendering, and saving map data for both Light and Dark Worlds.
- Introduced new canvas components for overworld map editing, allowing users to select and paint tiles directly onto the map.
- Enhanced the ScreenEditor with controls for tile flipping and palette selection, improving the user interface for overworld map management.

Benefits:
- Expands the capabilities of the ScreenEditor, providing users with tools to edit and manage the overworld map effectively.
- Improves user experience by enabling intuitive tile editing and visual feedback during map modifications.

src/zelda3/screen/title_screen.h

@@ -33,6 +33,10 @@ class TitleScreen {
   auto& bg1_buffer() { return tiles_bg1_buffer_; }
   auto& bg2_buffer() { return tiles_bg2_buffer_; }
   auto& oam_buffer() { return oam_data_; }
+  
+  // Mutable accessors for editing
+  auto& mutable_bg1_buffer() { return tiles_bg1_buffer_; }
+  auto& mutable_bg2_buffer() { return tiles_bg2_buffer_; }
 
   // Accessors for bitmaps
   auto& bg1_bitmap() { return tiles_bg1_bitmap_; }
@@ -47,6 +51,18 @@ class TitleScreen {
   // Save changes back to ROM
   absl::Status Save(Rom* rom);
 
+  /**
+   * @brief Render BG1 tilemap into bitmap pixels
+   * Converts tile IDs from tiles_bg1_buffer_ into pixel data
+   */
+  absl::Status RenderBG1Layer();
+
+  /**
+   * @brief Render BG2 tilemap into bitmap pixels
+   * Converts tile IDs from tiles_bg2_buffer_ into pixel data
+   */
+  absl::Status RenderBG2Layer();
+
  private:
   /**
    * @brief Build the tile16 blockset from ROM graphics
@@ -60,18 +76,6 @@ class TitleScreen {
    */
   absl::Status LoadTitleScreen(Rom* rom);
 
-  /**
-   * @brief Render BG1 tilemap into bitmap pixels
-   * Converts tile IDs from tiles_bg1_buffer_ into pixel data
-   */
-  absl::Status RenderBG1Layer();
-
-  /**
-   * @brief Render BG2 tilemap into bitmap pixels
-   * Converts tile IDs from tiles_bg2_buffer_ into pixel data
-   */
-  absl::Status RenderBG2Layer();
-
   int pal_selected_ = 2;
 
   std::array<uint16_t, 0x1000> tiles_bg1_buffer_;  // BG1 tilemap (32x32 tiles)