fix(audio): off/on Audio + Video toggles; fix Safari autoplay + GPU video-off

Operator-driven live-UI revision:
- Video + Audio are now Dev-Mode-style on/off toggles (Audio on = soundtrack);
  white-noise deferred (removed from the live control; pure machinery kept).
- FIX video-off not blanking: the <video>/<canvas> are GPU-composited and could
  paint above the auto-z #black on a real GPU — give #black z-index + its own
  layer AND hide the video layers (opacity 0) on video-off.
- FIX no soundtrack on Safari/iOS: Safari unlocks <audio> only when play() runs
  INSIDE the user gesture; the start gesture now primes both A/B elements
  synchronously, so the async crossfades are allowed to play.
- Toggles wired on 'change' (matches the Dev Mode switch).
- player/audio.py AUDIO_SOURCES -> {off, soundtrack}; tests + E2E updated.
- Verified in headless Chromium AND WebKit: audio plays, video-off blanks both
  layers, zero JS errors. 288 tests + 3 Playwright E2E pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

player/audio.py

@@ -2,17 +2,18 @@
 §4/§6). The single source of truth for: whether the projector shows video, and
 which audio url plays for a given (audio source, current altitude).
 
-Replaces player/content.py's 7-way bundled table. White-noise is a global,
-altitude-independent bed; soundtrack follows the single Altitude dial; off is
-silence. `music` is a reserved, deferred source — not in v1."""
+Replaces player/content.py's 7-way bundled table. Soundtrack follows the single
+Altitude dial; off is silence. `white_noise` and `music` are deferred sources —
+not in v1 (the live control is a simple Audio on/off toggle where on=soundtrack)."""
 
 from __future__ import annotations
 
 from dataclasses import dataclass
 
 VISUAL_POSITIONS = frozenset({"on", "off"})
-# v1 audio sources. "music" is reserved/deferred (no assets) and intentionally absent.
-AUDIO_SOURCES = frozenset({"off", "soundtrack", "white_noise"})
+# v1 audio sources. The live UI is an Audio on/off toggle (on=soundtrack).
+# "white_noise" and "music" are deferred (no live control) and intentionally absent.
+AUDIO_SOURCES = frozenset({"off", "soundtrack"})
 
 
 @dataclass(frozen=True)
@@ -31,24 +32,22 @@ def resolve_visual(position: str) -> bool:
     return position == "on"
 
 
-def resolve_audio_url(source: str, *, scale_audio: str, noise_url: str) -> str | None:
+def resolve_audio_url(source: str, *, scale_audio: str) -> str | None:
     """The audio url for (source, current altitude): soundtrack → the current
-    scale's asset (or None if none authored); white_noise → the global bed; off →
-    None. `scale_audio` is the ring scale's `audio` path (relative to /media/audio/)."""
+    scale's asset (or None if none authored); off → None. `scale_audio` is the ring
+    scale's `audio` path (relative to /media/audio/)."""
     if source not in AUDIO_SOURCES:
         raise ValueError(
             f"unknown audio source {source!r}; expected one of {sorted(AUDIO_SOURCES)}"
         )
     if source == "off":
         return None
-    if source == "white_noise":
-        return noise_url
     # soundtrack — couple to the current altitude's asset
     return f"/media/audio/{scale_audio}" if scale_audio else None
 
 
-def resolve_audio(source: str, *, scale_audio: str, noise_url: str) -> AudioResolution:
+def resolve_audio(source: str, *, scale_audio: str) -> AudioResolution:
     """The full render.audio view: source, resolved url, and whether it follows the
     Altitude dial (true only for soundtrack)."""
-    url = resolve_audio_url(source, scale_audio=scale_audio, noise_url=noise_url)
+    url = resolve_audio_url(source, scale_audio=scale_audio)
     return AudioResolution(source=source, url=url, altitude_coupled=(source == "soundtrack"))

player/controls.py

@@ -2,7 +2,7 @@
 
 This is the serial-contract payload shared with sub-project 4 (firmware). It
 models the full panel from the audio spec §3: a Visual toggle (on/off) + an
-Audio source selector (off/soundtrack/white_noise), the four experience knobs
+Audio source selector (off/soundtrack; white-noise/music deferred), the four experience knobs
 (0..4), and the two intensity levels (volume, brightness). The wire framing
 itself is the separate 3<->4 serial contract; this module is the *decoded* form.
 """

player/state.py

@@ -36,12 +36,12 @@ class TransitionKind:
 class Playback:
     """What should currently be playing. Visual and audio are orthogonal (audio
     spec §2): `video` is whether the projector shows footage, `audio_source` is
-    the independent audio dial (off / soundtrack / white_noise)."""
+    the independent audio dial (off / soundtrack)."""
 
     clip_id: Optional[str]            # None = black walls
     plan: Optional[RenderPlan]        # None when black
     video: bool                       # whether footage is shown (Visual on/off)
-    audio_source: str                 # the Audio dial source (off/soundtrack/white_noise)
+    audio_source: str                 # the Audio dial source (off/soundtrack)
     volume: int
     brightness: int