Venues: persistent room, motivated camera, ride; drop Pylon Grid

- Venue as one continuous place: persistent per-song layer, interpolated
  venueState, story jumps (one re-hang max + recap) with camera cuts
- Room camera shot plan (venueShots.js): per-section size/target, monotonic
  look sweep, traverse glide body, room-side alternation
- New Ride venue: generated vehicle + actor passengers, radio RTT screen,
  chase/stationary modes, ride archetype across generator/camera/staging
- Flora cost trim (5x(12+6+6) -> 4x(8+4+4) SDF evals, 204ms -> 140ms worst)
- Delete Pylon Grid shader (2.5s/frame SwiftShader); drop its metadata row
- tools/venue-check.js headless gate harness + venue-gallery explorer

flow-state/tools/lint-scenes.js

@@ -39,7 +39,7 @@ const FORBIDDEN = [
 ];
 
 // Directories whose output must be a pure function of (seed, params, frame).
-const DETERMINISTIC_DIRS = ['engine', 'scenes', 'look', 'audio', 'params', 'actors'];
+const DETERMINISTIC_DIRS = ['engine', 'scenes', 'look', 'audio', 'params', 'actors', 'venues'];
 // Files legitimately allowed a wall clock: perf measurement, not image content.
 const ALLOWED = new Set(['engine/perf.js']);