feat(audio): Visual×Audio Python contract — resolver, controls, state, API

- player/audio.py: pure resolve_visual / resolve_audio_url / resolve_audio (§4/§6)
- retire player/content.py (7-way table) + its test
- player/controls.py: serial contract content -> visual + audio
- player/state.py: Playback carries video:bool + audio_source:str
- simulator/app.py: /api/alteration validates visual+audio, returns render.video
  + server-resolved render.audio.url from altitude_index; NOISE_URL constant
- tests reframed; full suite 285 passed, 2 skipped

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

player/audio.py

@@ -0,0 +1,54 @@
+"""Resolve the orthogonal Visual × Audio controls into render outputs (audio spec
+§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."""
+
+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"})
+
+
+@dataclass(frozen=True)
+class AudioResolution:
+    source: str
+    url: str | None
+    altitude_coupled: bool
+
+
+def resolve_visual(position: str) -> bool:
+    """Visual on/off → whether the renderer shows video (vs fade-to-black)."""
+    if position not in VISUAL_POSITIONS:
+        raise ValueError(
+            f"unknown visual position {position!r}; expected one of {sorted(VISUAL_POSITIONS)}"
+        )
+    return position == "on"
+
+
+def resolve_audio_url(source: str, *, scale_audio: str, noise_url: 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/)."""
+    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:
+    """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)
+    return AudioResolution(source=source, url=url, altitude_coupled=(source == "soundtrack"))