Add NPC theater poses: sit, photo, film, perform

Once an NPC reaches its intent waypoint it now does something instead of standing
in an idle T-pose:

- sit: the rig settles 0.34 m into a seat and the legs swing forward on the steps
- photo/film: influencers and tourists raise their camera prop briefly (a sine
  pulse, so it reads as taking a shot rather than a permanently raised arm)
- perform: performers sway the sign board they carry

Pose selection lives in NpcAvatar.theater_pose() (intent + arrived); the math is in
pure helpers (crouch_for_pose, prop_lift_for_pose, sway_for_pose) so it is
headless-testable. Prop/leg nodes are captured at build time and animated from
their rest offsets. Performers also get a hand-held board and post.

Tests/docs
- Headless suite 120 -> 127 (test_npc_theater.gd).
- Verified visually with a staged sit/photo/perform lineup in front of the entrance.
- README, TODO section moved to DONE, MEMORY. Version 0.2.7.

TODO.md

@@ -1,19 +1,10 @@
 # TODO
 
-Godot 4.3 prototype. Release **v0.2.6** is tagged. Headless suite **120/120**, plus
-`smoke_session_shell.gd`, `smoke_plan_verbs.gd`, `smoke_crowd.gd`, `smoke_emergency.gd`,
-`smoke_timeline.gd`, and the windowed focus/radial smoke.
+Godot 4.3 prototype. Release **v0.2.7** is tagged. Headless suite **127/127**, plus the session,
+PLAN-verb, crowd, emergency, timeline, and windowed focus/radial smokes.
 
 Host `REQUIRE_SIGNIN_VIEW` stays deferred.
 
-## NPC theater
-
-Intents `sit` / `photo` / `film` / `perform` already pick waypoints. ADR-0010 rig (face/hair)
-is in the working tree. Bodies still idle-stand at those spots.
-
-- [ ] Sit pose at `steps_end`. Photo: brief raise of the influencer/tourist prop. Performer
-      stays put and plays the hat/sign.
-
 ## Audio
 
 `AudioFeedback` is sine beeps. DONE called that "crowd ambience"; it is not.