Add crowd presentation, fix NPC navigation, refresh screenshots

NPC navigation (previously dead in the live game)
- Only assign NavigationAgent3D.target_position when it changes: re-assigning every
  frame invalidated the path, so get_next_path_position() kept returning the current
  point and avatars never moved.
- Follow the first path point that is closer to the destination than the avatars are.
  Nav points sit on the navmesh plane (y=0) while bodies stand at y~0.5, so the old
  3D distance test always looked "already there"; path[0] is also the old start point,
  so a naive "far enough away" pick steered backwards and oscillated.
- Fix fsm.state -> fsm.current_state in the idle-lifetime check.

Crowd presentation
- Aggressive behavior, visible weapons, and responder arrivals make idle bystanders
  stop and face the incident for 12 s; someone waiting at the entrance keeps focus.
- Panic (mood >= 0.75) walks people away from the door at 2.4 m/s, then they despawn.
- Wire reactions to EventBus.crowd_changed: CrowdSystem.apply_event() emits on the bus,
  not on its own `changed` signal (the first wiring received nothing).
- Measured a 16-NPC entrance at ~1.2 ms/frame (824 fps, vsync off), so no LOD/culling.

World and HUD
- Skyline is now a ring of four alpha-scissored planes at 200 m instead of a single
  plane; PlaneMesh defaults to horizontal, which is why the backdrop rendered as a band
  overhead. Larger ground plane, mipmapped texture, scissor threshold 0.5 (0.3 left
  mip dashes in the sky), lifted albedo so the city is not pure black.
- Flashlight aims straight ahead and lights the person/door instead of the ground.
- Shorter HUD controls line so it stops overlapping itself.

Tests, tooling, docs
- Headless suite 98 -> 105 (new test_crowd_presentation.gd, 7 tests).
- New smoke_crowd.gd: rubbernecking, panic, and flee-target sanity.
- capture_screenshots.gd starts a shift from the venue menu and stages the night set
  properly; all six README screenshots regenerated.
- README, TODO/DONE (crowd section moved), MEMORY updated. Version 0.2.4.

TODO.md

@@ -1,20 +1,11 @@
 # TODO
 
-Godot 4.3 prototype. Release **v0.2.3** is tagged; CI builds the installers and AppImage.
-Headless suite **98/98**, plus `smoke_session_shell.gd`, `smoke_plan_verbs.gd`, and the windowed
-focus/radial smoke.
+Godot 4.3 prototype. Release **v0.2.4** is tagged; CI builds the installers and AppImage.
+Headless suite **105/105**, plus `smoke_session_shell.gd`, `smoke_plan_verbs.gd`,
+`smoke_crowd.gd`, and the windowed focus/radial smoke.
 
 Host `REQUIRE_SIGNIN_VIEW` stays deferred.
 
-## Crowd presentation
-
-`CrowdSystem` is a mood/attention float. PLAN wants people watching, gathering, and panicking.
-
-- [ ] On `aggressive_behavior` / `emergency_responder`, nearby idle NPCs stop and face the
-      incident (rubberneck). On `crowd_panic`, they move away from the door.
-- [ ] Profile a busy entrance with textured materials and props; add LOD or culling for distant
-      NPCs if frame time drops.
-
 ## Emergency aftermath
 
 Responder outcomes (`command` / `restraint` / `evacuation` / `arrest`) are log lines. PLAN also