fix(skill): reconcile SFX drift tolerance to ±0.1s across script + prose

Vai (vanceingalls) caught a 10× tolerance mismatch between the script
and the prose. Rames confirmed as blocking:

  step-5-build.md:458 (per-beat evidence rule):  ±0.05s
  step-6-validate.md     (playback verification):  ±0.1s
  w2h-verify.mjs:29 (SFX_DRIFT_TOLERANCE_S):       0.5s

So an agent writing per-beat evidence at ±0.05s reports a 0.3s drift
as FAIL, while the script reports the same drift as PASS. The pasted-
verbatim report contradicts the agent's evidence block — exactly the
kind of internal contradiction this PR was built to eliminate.

Converged on ±0.1s everywhere:

- w2h-verify.mjs:29: SFX_DRIFT_TOLERANCE_S = 0.1 (3 frames at 30fps)
- step-5-build.md:458: ±0.05s → ±0.1s, with cross-reference noting it
  matches the script + step-6 playback floor

The other ±0.5s constants in step-6 are for total audio/video duration
and storyboard beat-range matching — those are coarser-grained timing
checks (not SFX-to-visual sync). Left as-is intentionally.

Regression check: huly-v3 now flags 4 SFX drifts instead of 3 — the
new one is glitch-1.mp3 at 0.20s drift (6 frames). The old 0.5s
tolerance was masking this real timing issue.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ukimsanov

skills/website-to-hyperframes/references/step-5-build.md

@@ -455,7 +455,7 @@ For each SFX entry:
 3. Add beat-local + global start: `3.5 + 1.2 = 4.7s`.
 4. Write `data-start="4.7"` in index.html.
 
-**Forbidden:** writing `data-start="<approximate visual moment>"` by reading the storyboard and estimating by eye. The evidence block above MUST quote both the storyboard SFX line and the index.html `data-start` line — and confirm they match within ±0.05s. A 1-second drift is not a rounding error; it's a build failure.
+**Forbidden:** writing `data-start="<approximate visual moment>"` by reading the storyboard and estimating by eye. The evidence block above MUST quote both the storyboard SFX line and the index.html `data-start` line — and confirm they match within ±0.1s (≈3 frames at 30fps; same tolerance `w2h-verify.mjs` enforces and `step-6-validate.md` uses for playback verification). A 1-second drift is not a rounding error; it's a build failure.
 
 ### Surface recurring sub-agent workarounds to the user
 

skills/website-to-hyperframes/scripts/w2h-verify.mjs

@@ -26,7 +26,7 @@ const PROJECT_DIR = resolve(process.argv[2] || ".");
 // Thresholds — change here, not by interpretation.
 const HEADLINE_MIN_PX = 80; // 80px floor for primary headline at 1920×1080
 const TIMELINE_COVERAGE_MIN = 0.7; // max GSAP event position must reach ≥70% of beat duration
-const SFX_DRIFT_TOLERANCE_S = 0.5;
+const SFX_DRIFT_TOLERANCE_S = 0.1; // 3 frames at 30fps; matches step-5 evidence rule + step-6 playback floor
 const BEAT_DURATION_DRIFT_TOLERANCE_S = 0.5;
 
 const SHADER_NAMES = [