VOID DECOR (M18b): the empty air gets furniture — drifting shoals, ships, ghosts, meteors

New generative system, zero perturbation of existing streams (new labeled
family "void-decor"):
- gen/endless/voidDecor.ts: per-segment clusters (0-2, expected ~1) of
  1-5 pieces hung off the segment's own path samples — mid band 8-16u
  (slightly below the line), far band 18-40u scaled into fog silhouettes;
  biome-flavored tables (ships off tropical coasts, a ghost + crypt in
  spooky air, snowflakes in winter, sand shoals in autumn) + generic
  rock/crystal shoals; rare far-band EVENTS ~0.08 (meteor trains, a
  passing craft/satellite) with pure-in-index quiet-after suppression.
  Sites keep >=6u of every path sample (main+alt), island cells, and any
  occupancy claim at their column. Space Kit imported (153 pieces).
- EndlessSegment.voidDecor is a SEPARATE field: the proxy path
  structurally cannot see it — non-collision by construction (contract
  test: proxies byte-count-identical with the field stripped).
- Placement.float {amp, period, phase, drift} — the wind model: canon
  hashes it; genVersion untouched (finite never emits it).
- client/voidRender.ts: instanced flat in the frame-correct segment
  group (spawn/exit waves see direct children; twist halves split per
  anchor), castShadow off, no occluder flag; float pass in finishFrame
  gated on the spawn wave (writer-overlap-free) with a 2s bob envelope +
  capped segment-local drift; fit box skips voidDecor-flagged meshes
  (far shoals must not inflate shadow/focus).
- Tests: same-seed determinism, 30x8 structural scan (budget, clearance,
  resolution, float-on-every-piece, multi-pack emergence), proxy
  blindness contract, event rarity + never-consecutive law.
  188 green, check clean. Endless goldens re-pinned (canon + content);
  genVersion g491fc4c7a685 unchanged.

commit

74731b242648c8051e0cd701703bffcc99804114

parent

ad5a11148863dca8b4d2d345465fe3982e7cbdd9

author

Dami <dami.etoile@gmail.com>