t27f token_floor: PBR gold balls, a story of shots with spec cards, tall and wide cuts from one world #10451

Boundary

specs/t27f/pbr_sphere.t27 (new), specs/t27f/token_floor_scenes.t27 (new), specs/t27f/token_floor.t27, specs/t27f/token_floor_mux.t27, their four seals under .trinity/seals/, and the token_floor comment in tools/verilog_width_baseline.txt. No foreign code: every change is a .t27 spec, a seal t27c wrote, or prose. ffmpeg stays the muxer, driven by the filter graphs token_floor_mux prints.

User Scenarios

• The owner watched the gold token_floor reel (t27f token_floor reel: letters in Outfit ExtraBold, captions in JetBrains Mono (t27.ai's own fonts) #10376) and said four things: the balls do not look real, so bring 3D best practice into t27f; render a horizontal 1920x1080 and a vertical 1080x1920 cut together; make the captions gold too, one style; and one scene is boring, so the transitions between shots should tell a story of scenes (with tetsuo's AI-interface reels as the reference for taste).
• A reviewer wants the realism claims checkable: GGX normalisation, Schlick Fresnel for gold, the split sum and the shutter's area are all tested numbers, not adjectives.
• Master sped the renderer up in t27f: token_floor renders in 48 shards; frames cached by the seal (Closes #10383) #10384, t27f token_floor: a per-frame row index, so each raster row visits only the splats that touch it (Closes #10391) #10402 and t27f token_floor: expose only the pixels a splat visited; the empty scene's bytes are computed once (Closes #10407) #10411; this work must keep those speedups where they still hold, and say plainly where one no longer holds.

Requirements

• pbr_sphere.t27 shades a ball as a physically based metal or dielectric: GGX microfacets, Schlick Fresnel with gold's coloured F0, Karis's split-sum fit, an analytic softbox rig and horizon, mirrored neighbours, analytic sphere occlusion at contacts, and a 180 degree shutter's time-averaged disk.
• token_floor_scenes.t27 cuts the reel into shots: a camera per shot (push-ins, moves, dollies on a smootherstep), hard cuts timed just before a narration event, translucent spec cards showing the t27 function behind the number on screen with a green PASS, and small mono scene tags.
• token_floor.t27 renders both cuts from one world, tall first then wide, with the PBR balls, the camera and the cards; it keeps master's shards (TF_SHARD/TF_SHARDS, plus TF_CUT to pick one cut) and the row index (with a full-scan fallback when zoom or blur would overflow INDEX_CAP). The cached empty scene of t27f token_floor: expose only the pixels a splat visited; the empty scene's bytes and row factors are computed once #10407 is dropped: the camera moves and the lens dithers every frame, so no two frames share one.
• token_floor_mux.t27 prints one filter graph per cut; captions are the reel's gold and stay clear of the scene, the card and the tags in both cuts.

Success Criteria

• The t27c test report passes on pbr_sphere, token_floor_scenes, token_floor and token_floor_mux with no vacuous tests, and all four seal.
• Both reels are 15.000 s at 30 fps (1080x1920 and 1920x1080), near -14 LUFS, captions measured gold in both cuts.
• The four TF_CUT=0 shards concatenated equal the tall cut of the one-process render, byte for byte.