feat(audio): Phase E.2 OpenAL engine + SoundTable cookbook + hook wiring

Full audio pipeline from MotionHook → OpenAL 3D playback. Faithful to
retail's 16-voice pool, inverse-square falloff, and SoundTable
probabilistic variant selection.

Core layer (AcDream.Core/Audio):
- WaveDecoder parses the WAVEFORMATEX in Wave dat headers. PCM
  (wFormatTag=1) decodes directly; MP3 (0x55) and ADPCM (0x02) return
  null + log (ACM compressed decoders need Windows winmm; cross-platform
  path deferred). Cites r05 §2.1-2.3 + ACE Wave.cs.
- SoundCookbook.Roll implements the probability-weighted entry pick that
  gives retail footsteps their variation. Cumulative-distribution walk;
  silence tail when probabilities sum to <1.
- DatSoundCache: ConcurrentDictionary-backed lazy load of Wave /
  SoundTable dats, decoded PCM memoized.

App layer (AcDream.App/Audio):
- OpenAlAudioEngine (Silk.NET.OpenAL): 16-source 3D pool with
  round-robin first-free, then evict-quieter-slot algorithm matching
  retail chunk_00550000.c FUN_00550ad0 exactly. Separate 4-source UI
  pool (source-relative). AL buffer cache keyed by Wave id.
  InverseDistanceClamped distance model. Fail-open when AL driver
  missing or ACDREAM_NO_AUDIO=1 — client continues without audio.
- AudioHookSink routes SoundHook / SoundTableHook / SoundTweakedHook
  from the Phase E.1 animation-hook router into OpenAL. All three
  hook types fire on both player AND NPCs/monsters (the sequencer
  dispatches per-entity and the sink uses entity worldPos for 3D pan).
- DictionaryEntitySoundTable holds per-entity SoundTable mapping,
  populated from Setup.DefaultSoundTable at hydration time. Server-
  sent overrides would take precedence here when wired.

GameWindow integration:
- OpenAL init in OnLoad after dat collection, suppressible via
  ACDREAM_NO_AUDIO=1.
- SetListener called each OnRender frame with camera position + view
  basis vectors (fwd = -Z, up = +Y of inverse view).
- AudioEngine disposed in OnClosing before dats.

Tests: 6 WaveDecoder (PCM / MP3-null / ADPCM-null / stereo / truncated
/ peek) + 6 SoundCookbook (empty / single / 50-30-20 distribution
within 5%, silence tail, table lookup, missing table key). Verified
against r05 §2 + ACViewer export-path.

Build green, 497 tests pass (up from 485).

Ref: r05 §2 (Wave format), §5.3 (16-voice pool + eviction).
Ref: FUN_00550ad0 (chunk_00550000.c:527) eviction algorithm.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -129,6 +129,13 @@ public sealed class GameWindow : IDisposable
     // per-entity tick loop can just call it unconditionally.
     private readonly AcDream.Core.Physics.AnimationHookRouter _hookRouter = new();
 
+    // Phase E.2 audio. Null when ACDREAM_NO_AUDIO=1 or the OpenAL driver
+    // failed to init; all three are set together.
+    private AcDream.App.Audio.OpenAlAudioEngine? _audioEngine;
+    private AcDream.Core.Audio.DatSoundCache? _soundCache;
+    private AcDream.App.Audio.DictionaryEntitySoundTable? _entitySoundTables;
+    private AcDream.App.Audio.AudioHookSink? _audioSink;
+
     // Phase B.2: player movement mode.
     private AcDream.App.Input.PlayerMovementController? _playerController;
     private AcDream.App.Rendering.ChaseCamera? _chaseCamera;
@@ -559,6 +566,33 @@ public sealed class GameWindow : IDisposable
         _dats = new DatCollection(_datDir, DatAccessType.Read);
         _animLoader = new AcDream.Core.Physics.DatCollectionLoader(_dats);
 
+        // Phase E.2 audio: init OpenAL + hook sink. Suppressible via
+        // ACDREAM_NO_AUDIO=1 for headless tests / broken audio drivers.
+        if (Environment.GetEnvironmentVariable("ACDREAM_NO_AUDIO") != "1")
+        {
+            try
+            {
+                _soundCache = new AcDream.Core.Audio.DatSoundCache(_dats);
+                _audioEngine = new AcDream.App.Audio.OpenAlAudioEngine();
+                _entitySoundTables = new AcDream.App.Audio.DictionaryEntitySoundTable();
+                if (_audioEngine.IsAvailable)
+                {
+                    _audioSink = new AcDream.App.Audio.AudioHookSink(
+                        _audioEngine, _soundCache, _entitySoundTables);
+                    _hookRouter.Register(_audioSink);
+                    Console.WriteLine("audio: OpenAL engine ready (16 voices, 3D positional)");
+                }
+                else
+                {
+                    Console.WriteLine("audio: OpenAL unavailable (driver missing / headless) — audio disabled");
+                }
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"audio: init failed: {ex.Message} — audio disabled");
+            }
+        }
+
         uint centerLandblockId = 0xA9B4FFFFu;
         Console.WriteLine($"loading world view centered on 0x{centerLandblockId:X8}");
 
@@ -1114,6 +1148,17 @@ public sealed class GameWindow : IDisposable
                 CurrFrame = idleCycle.LowFrame,
                 Sequencer = sequencer,
             };
+
+            // Phase E.2: register entity's SoundTable so SoundTableHook can
+            // resolve creature-specific sounds (footsteps, attack vocalizations,
+            // damage grunts, etc). Server-sent SoundTable override would take
+            // precedence here when the wire layer delivers it.
+            if (_entitySoundTables is not null)
+            {
+                uint soundTableId = (uint)setup.DefaultSoundTable;
+                if (soundTableId != 0)
+                    _entitySoundTables.Set(entity.Id, soundTableId);
+            }
         }
 
         // Dump a summary periodically so we can see drop breakdowns without
@@ -2702,6 +2747,21 @@ public sealed class GameWindow : IDisposable
             // Extract camera world position from the inverse of the view matrix.
             System.Numerics.Matrix4x4.Invert(camera.View, out var invView);
             var camPos = new System.Numerics.Vector3(invView.M41, invView.M42, invView.M43);
+
+            // Phase E.2 audio: update listener pose so 3D sounds pan/attenuate
+            // correctly relative to where we're looking. Fwd = -Z of the view
+            // matrix (OpenGL convention), up = +Y. Both live in the inverse
+            // view matrix's basis vectors.
+            if (_audioEngine is not null && _audioEngine.IsAvailable)
+            {
+                var fwd = new System.Numerics.Vector3(-invView.M31, -invView.M32, -invView.M33);
+                var up  = new System.Numerics.Vector3( invView.M21,  invView.M22,  invView.M23);
+                _audioEngine.SetListener(
+                    camPos.X, camPos.Y, camPos.Z,
+                    fwd.X, fwd.Y, fwd.Z,
+                    up.X,  up.Y,  up.Z);
+            }
+
             var visibility = _cellVisibility.ComputeVisibility(camPos);
             bool cameraInsideCell = visibility?.CameraCell is not null;
 
@@ -3166,6 +3226,7 @@ public sealed class GameWindow : IDisposable
         // _dats; Dispose cancels the token and waits up to 2s for the thread.
         _streamer?.Dispose();
         _liveSession?.Dispose();
+        _audioEngine?.Dispose();  // Phase E.2: stop all voices, close AL context
         _staticMesh?.Dispose();
         _textureCache?.Dispose();
         _meshShader?.Dispose();