feat: eval/exec of strings, gallery Replay, callable actions; iNSight and SomethingBetter now pass

- pyparse.ts: parser for expressions and simple statements built at run time, producing
  the sandbox's own IR; backs eval() and exec() (e.g. exec("persistent." + var + " = 0"))
- Replay/EndReplay and renpy.end_replay: the engine stashes the full game state, runs the
  label with the given scope and restores everything when it ends; locked replays are
  insensitive. Save loading shared as applySave()
- Screen actions are callable (MainMenu(confirm=False)())
- jump main_menu_screen is Ren'Py's own label: it opens the player's main menu
- Screens: a closing quote ends the word before a letter ("text"size 15) but not before
  an operator ("a"+b); Text(...) pictures in image blocks
- README: current capabilities and limits of the Ren'Py support

Strict compatibility check on the local collection: Tomie, Twisted-Thoughts, Hooked,
iNSight-of-you and SomethingBetter pass; TheFixer (custom AlphaMask wardrobe, missing
labels) and That_New_Teacher (custom statements, Render API) do not.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

backend/app/converter/rpy_helpers.py

@@ -18,7 +18,7 @@ _SHOW_KEYWORDS = {"at", "as", "behind", "onlayer", "with", "zorder"}
 _NUMBER_LINE = re.compile(r"^\d+(\.\d*)?$|^\.\d+$")
 _CALL_LINE = re.compile(r"^([A-Za-z_][\w.]*)\s*\(")
 _DISPLAYABLE_CALLS = {"Movie", "Solid", "Transform", "Composite", "LiveComposite", "Fixed",
-                      "ConditionSwitch", "Image", "im.Scale", "im.FactorScale", "im.Flip",
+                      "ConditionSwitch", "Image", "Text", "im.Scale", "im.FactorScale", "im.Flip",
                       "im.Composite", "im.Crop", "im.Grayscale", "im.Sepia", "Frame", "Flatten"}
 _MEDIA_EXTS = {"png", "jpg", "jpeg", "webp", "gif", "bmp", "avif", "ogg", "mp3", "wav", "opus",
                "flac", "webm", "ogv", "mp4", "mkv", "avi", "m4a"}