feat: improve RenPy conversion and support MIST runtime

backend/app/games/renpy_native.py

@@ -0,0 +1,30 @@
+"""Third-party Ren'Py libraries that the player implements natively.
+
+Some community snippets are Python classes written against Ren'Py's render API (``renpy.Displayable``,
+``renpy.Render``, pygame events). The browser player cannot run that API, so it ships its own class of the
+same name and the converter drops the game's copy. Everything the converter needs to know about them lives
+here; add an entry together with the TypeScript implementation (``nativeClasses`` in ``python.ts`` or the
+displayable in ``screens.ts``), never in the shared converter code.
+"""
+
+#: class name -> what the native version offers
+NATIVE_CLASSES: dict[str, dict] = {
+    "Gallery": {"methods": ("button", "image", "display", "make_button", "Action", "unlock", "unlock_image", "condition")},
+    # parallax picture that drifts against the mouse (screens: ``add TrackCursor("bg.png", 20)``)
+    "TrackCursor": {"methods": ()},
+    # Feniksdev's colour picker; the native class keeps the chosen colour and slot, the game draws its own UI
+    # Ren'Py's own MusicRoom, which games subclass; the player ships the playlist logic (musicroom.ts)
+    "MusicRoom": {"methods": ("add", "is_unlocked", "get_playlist", "Play", "Stop", "TogglePause", "Next",
+                              "Previous", "RandomPlay", "SetLoop", "ToggleLoop", "SetSingleTrack",
+                              "ToggleSingleTrack", "SetShuffle", "ToggleShuffle", "UnlockAll", "LockAll")},
+    "ColorPicker": {"methods": ("set_color", "save_color", "set_saved_color", "get_color", "swap_to_saved_color")},
+}
+
+#: modules those classes import for their event handlers; harmless once the class is replaced
+NATIVE_IMPORTS = {"pygame"}
+
+# These image factories are lowered to image IR by displayable_expr, rather than
+# instantiated in Python. Their render-API classes must not execute at startup.
+COMPILED_IMAGE_CLASSES = {"TransitionConditionSwitch"}
+
+NATIVE_METHODS = {m for spec in NATIVE_CLASSES.values() for m in spec["methods"]}