Author the missing scenario content from the PLAN lists

Joke Shop
- Reservation list without ID (guest list valid, ID missing) — denied.
- Borrowed/mismatched ID (ID valid but mismatched) — denied.
- Guest who refuses the wand screen: new `refuses_screening` event flag, copied
  onto NPCController, handled in _toggle_wand_screening (logs wand.refused, records
  a wand_refused event, small prop hit, panel stays closed).
- Late arrival during the performance (ID + ticket, "arrive" intent).

Studio
- Filming-boundary event and a later repeat, both using the new `film_boundary`
  intent which maps to `steps_end` so the influencer stands past the posted line.
- Celebrity arrival now pulls in a small crowd via a new `extra_spawns` event field
  (two tourists + an influencer), spawned through the normal path.

Building
- Filming-boundary event whose hint points at the body camera and request-reason
  verbs, plus an unclear-intent event that hints at asking for a reason.

Engine support
- Events may carry `hint` (string key logged on spawn), `extra_spawns`, and
  `refuses_screening`; 9 new localized hint strings.

Tests/docs
- Headless suite 139 -> 149 (test_scenario_content.gd) and a new
  smoke_scenario_content.gd that spawns the refusal and celebrity events through the
  real signal path.
- README, TODO section moved to DONE, MEMORY. Version 0.2.13.

content/strings.en.json

@@ -56,6 +56,15 @@
   "reason.ask": "You ask %s why they are here.",
   "reason.reply": "%s: \"%s\"",
   "reason.silent": "%s says nothing and looks away.",
+  "hint.reservation_no_id": "On the reservation list but no ID — ask for ID, then check the list.",
+  "hint.borrowed_id": "The ID photo does not match the person. Verify before admitting.",
+  "hint.refuses_wand": "This guest refuses the wand screen. No screen, no entry.",
+  "hint.late_arrival": "Late arrival during the performance — check ID and ticket before opening the door.",
+  "hint.film_boundary": "Filming past the posted line. Ask their reason and point them back to the sidewalk.",
+  "hint.film_boundary_repeat": "Same crew again, still past the line. A formal warning is now reasonable.",
+  "hint.celebrity_arrival": "Celebrity arrival: the crowd is swelling. Keep the entrance clear.",
+  "hint.body_camera_reason": "They are filming the entrance. Ask their reason (Reason) and consider the body camera (B).",
+  "hint.ask_reason": "Unclear intent. Ask why they are here (Reason) before deciding anything else.",
   "station.blocking": "You step between %s and the door.",
   "perception.near": "%s notices you standing close.",
   "perception.aware": "%s notices you watching.",