feat(editor): complete level editor integration and fixes

[alfonsoalvarohervas-sudo]

As requested in the feedback for splitting PR #165 , this Pull Request isolates the Level Editor feature. It has been built and rebased cleanly against the latest upstream/master, removing all unrelated engine bugfixes.

This feature allows developer/modder painting and saving of custom level maps directly from the GBA PC port runtime using an ImGui overlay.

Detailed Changes per File

• port/port_level_editor.cpp (NEW)

  • Implements the complete Level Editor backend.
  • Handles mouse tile painting, eyedropper sampling, undo/redo states, and custom entity vectors loading/parsing.
  • Implements the custom level saving logic (SaveCurrentRoom) to output binary file layouts to edited_levels/area%02X_room%02X.bin.
  • Implements the loader logic (Port_LevelEditor_OnRoomLoad) to parse saved levels and rebuild collision matrices.
  • Implements the rendering logic using SDL_Renderer primitives (outline overlay, tile previews, overlay sidebar).

• port/port_level_editor.h (NEW)

  • Declares the C-compatible linkage interface (Port_LevelEditor_*) to integrate with the GBA engine and port layer.

• xmake.lua (MODIFIED)

  • Added port/port_level_editor.cpp to the compile list of the main tmc_pc target.

• port/port_bios.c (MODIFIED)

  • Restored to the modern upstream/master version containing decoupled pacing variables.
  • Hooked keyboard events in Port_PumpEvents using Port_LevelEditor_HandleKey to capture layout hotkeys.
  • Hooked mouse button down/up events (Port_LevelEditor_HandleMouseButton) and mouse motion (Port_LevelEditor_HandleMouseMotion) when the editor is active to intercept clicks and prevent forwarding inputs to the GBA game thread.

• port/port_imgui_menu.cpp (MODIFIED)

  • Added the "Map Editor" tab to the F8 Ribbon menu (DrawRibbonMapEditorTab).
  • Added checkbox "Enable Direct Painting Overlay" to toggle editor state.
  • Automatically toggles the F8 debug menu off when the editor is enabled to immediately allow tile painting.
  • Hooked Port_LevelEditor_Render right before ImGui presentation to draw overlays on the SDL backend.

• port/port_ppu.cpp (MODIFIED)

  • Restored to the modern upstream/master version.
  • Changed Port_PPU_VisibleFrameWidth() declaration to extern "C" so it can be resolved inside the C++ level editor module.

• src/playerUtils.c (MODIFIED)

  • Added the call Port_LevelEditor_OnRoomLoad() to the end of the general room graphic initialization function LoadRoomGfx(). This ensures edited room binaries are loaded cleanly on warps, saves, transitions, and startup.

• include/room.h (MODIFIED)

  • Renamed RoomTransition to RoomTransitionType to avoid C++ linkage conflicts.

• src/game.c (RESTORED)

  • Restored to 100% parity with upstream/master.

---

Verification

• Syntactically clean and compiles cleanly on Windows.
• Verified that room modifications are persisted inside dist/<REGION>/edited_levels/ and load correctly upon room entry.
• Compatible with both software and GPU renderers (requires the sdl or software backend for overlay drawing).