Build distinct Joke Shop and TV Studio venues

Add the alley walls, warm lantern, shutters, dumpster, AC clutter and door
step for the Joke Shop. Build the studio stone facade, bulb canopy, glossy
black car, stanchions and barriers. Rebuild only the world container when the
venue changes, so the guard and UI survive; add per-venue navigation checks.
Capture gallery shots 12/13, update the concept mapping and docs. Headless
231/231, Python 87/87, screenshot gate 13 good/0 bad. The vision-judge retry is
tracked separately because the API key is invalid.

tools/screen_designs.py

@@ -369,7 +369,7 @@ SCREENS = [
         "kind": "scene",
         "title": "Joke Shop door queue",
         "source": "PLAN.md The Joke Shop — long line, ID and ticket checks",
-        "ref": None,
+        "ref": "12-joke-shop.png",
         "description": "Evening view of a small comedy-club entrance: a short queue "
                        "on the sidewalk, a door person checking an ID and a ticket "
                        "under a warm bulb, a red awning, and the show board.",
@@ -391,7 +391,7 @@ SCREENS = [
         "kind": "scene",
         "title": "TV Studio celebrity arrival",
         "source": "PLAN.md Late Night TV Studio — crowd gathers for an arrival",
-        "ref": None,
+        "ref": "13-studio-arrival.png",
         "description": "A celebrity arrival at the studio entrance: tourists and "
                        "influencers pressing toward the door, cameras raised, the "
                        "guard holding a line on the steps, studio marquee behind.",