Runtime hygiene: fix RefCounted cycles (clean suite exit), full-length shifts, wand cooldown

- FSM holds owner via WeakRef; ShiftCoordinator is RefCounted (logic-only);
  persistence tests free the Save node -> test suite exits with zero
  'resources still in use' warnings (was ~13) and 57/57 pass
- GameManager uses each scenario's shift_duration_s (900s ~ 10-15 min) for
  real shifts instead of the 300s test duration
- Wand screening gets a 0.8s recharge cooldown with a wand.recharge message
- TODO/DONE/MEMORY/README synced

MEMORY.md

@@ -62,12 +62,18 @@ Session memory for durable decisions, state, and gotchas. Keep concise, remove o
 - Detailed graphics: textured facade/awning/skyline, humanoid NPC rigs + props + walk bob +
   attention head-turn, inspection artifact cards, mode icons, escalation vignette, body-cam
   overlay (REC + shift clock). Screenshot set regenerated (`docs/screenshots/`, day + night).
+- Polish: wand scan cooldown (`WAND_COOLDOWN_S` + `wand.recharge` message).
 - NOTE: collaborators occasionally add uncommitted work to this shared tree (e.g. the radio
   easter egg); check `git status` before committing and leave foreign changes untouched unless asked.
 
 ## Known Issues / Notes
 
-- RefCounted reference cycle: `NPCController` holds an `FSM` that holds a back-reference to its owner, so test suites report "resources still in use at exit". Benign (process exit), but worth breaking later (e.g. `WeakRef` or explicit `dispose()`).
+- Reference cycles are fixed: `FSM` holds its owner via `WeakRef`, `ShiftCoordinator` is
+  `RefCounted`, and persistence tests free the `Save` node — the suite exits with no
+  "resources still in use" warnings (was ~13). If a future subsystem introduces a cycle,
+  repeat the WeakRef pattern.
+- Shift length: `GameManager` uses the scenario's `shift_duration_s` (900s ≈ 10-15 min);
+  tests and the screenshot tool override elapsed time directly.
 - Headless (dummy renderer) logs "Parameter m is null" from `mesh_get_surface_count`; it does not occur with a real GL driver and does not affect logic.
 - Steps are visual-only (no collider) so NPCs can path to the entrance; the guard spawns on the landing so it never needs to climb.
 - Persistence tests write into the real `user://shift_results.json` (harmless local pollution of the demo history).