feat(a2b): audio — wire play-bgm/play-voice, fix BGM addressing

Wire audio end-to-end (OGG plays natively in Godot; no Frida, no decode):
- IHost.PlayBgm/PlayVoice + VM dispatch for play-bgm(0xbf)/play-voice(0xc4).
  Non-Godot hosts no-op them so --selftest + engine 8/8 stay byte-identical.
- GodotAdvHost resolves id->OGG; Main plays via two AudioStreamPlayer nodes
  (BGM looping; voice interrupt-on-new).

Key finding (by-ear, systematic-debugging): the two audio ops use DIFFERENT
addressing — the earlier "unified manifest" assumption was wrong for BGM.
- play-voice -> per-scene manifest files[base+id] (offset 0, same as textures).
  Confirmed by ear; upgraded med->HIGH.
- play-bgm  -> DIRECT LITERAL NAME BGM{id:03d}.OGG, NOT the manifest.
  Real game: play-bgm 5->BGM005, 8->BGM008 (manifest gave +1). Proven by
  play-bgm 0x23->BGM035 (real standalone track; BGM set skips 030-034) that the
  manifest mis-resolved to a graphics entry. Fix is BGM-only:
  ResourceMap.BgmPathById; voices/textures unchanged.

Also: Lily's silence root-caused as correct form-gating (G[0xa57/0xa58/0xa59]),
left unseeded by choice (no dummy state). Added diagnostic
`Age.Cli audio <SCENE.BIN> [0xADDR=VAL ...]`. Corrected opcodes.toml (play-bgm
direct-name, play-voice HIGH) + docs/memory (dropped the bogus unified-manifest
/ Frida-BGM006 claims).

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

engine/Age.Cli/Program.cs

@@ -18,6 +18,30 @@ if (args[0] == "run")
     return 0;
 }
 
+if (args[0] == "audio")
+{
+    // audio <SCENE.BIN> — run the scene and dump executed play-bgm/play-voice ops in order,
+    // each resolved via ResourceMap (same rule as the Godot host). Diagnostic only.
+    var sceneName = args[1];
+    var sceneKey = Path.GetFileNameWithoutExtension(sceneName).ToUpperInvariant();
+    var res = ResourceMap.Load();
+    var host = new AudioTraceHost(res, sceneKey);
+    var vm = new VirtualMachine(Sys4Loader.Load(Paths.Scripts()[sceneName.ToUpperInvariant()], table), table, host);
+    // optional: seed globals, e.g. `audio SC0000.BIN 0xa57=1` to set Lily's form-A flag
+    foreach (var s in args.Skip(2))
+    {
+        var kv = s.Split('=');
+        int k = kv[0].StartsWith("0x") ? Convert.ToInt32(kv[0], 16) : int.Parse(kv[0]);
+        long v = kv[1].StartsWith("0x") ? Convert.ToInt64(kv[1], 16) : long.Parse(kv[1]);
+        vm.Globals[k] = v;
+    }
+    vm.Run();
+    Console.WriteLine($"{sceneName}: {host.Events.Count} audio ops (halt: {vm.HaltReason})");
+    foreach (var (kind, id, resolved) in host.Events)
+        Console.WriteLine($"  {kind,-10} 0x{id:x2} -> {resolved}");
+    return 0;
+}
+
 if (args[0] == "trace")
 {
     var scene = new Regex(@"^S[CP]\d{4}\.BIN$");
@@ -35,3 +59,29 @@ if (args[0] == "trace")
     return 0;
 }
 Console.WriteLine("unknown command"); return 1;
+
+sealed class AudioTraceHost : IHost
+{
+    private readonly ResourceMap _res;
+    private readonly string _scene;
+    public List<(string Kind, long Id, string Resolved)> Events { get; } = new();
+    public AudioTraceHost(ResourceMap res, string scene) { _res = res; _scene = scene; }
+    public void PlayBgm(long id)                        // BGM: direct name, not the manifest
+    {
+        var path = _res.BgmPathById(id);
+        Events.Add(("play-bgm", id, path != null ? $"DATA3 {System.IO.Path.GetFileName(path)}" : $"BGM{id:D3}.OGG <missing>"));
+    }
+    public void PlayVoice(long id)                      // voice: per-scene manifest
+    {
+        var e = _res.Resolve(_scene, id);
+        Events.Add(("play-voice", id, e == null ? "<unresolved>"
+            : $"{e.Archive} {e.Name}" + (ResourceMap.AudioPath(e) == null ? " [NO FILE]" : "")));
+    }
+    public void ShowText(int offset, string text) { }
+    public void CallScript(long id) { }
+    public void OnStub(int opcode) { }
+    public void WaitForInput() { }
+    public void CreateTexture(int slot, int width, int height) { }
+    public void SetTexture(long resourceId, int slot) { }
+    public void DrawTexture(int slot, int srcX, int srcY, int width, int height, int dstX, int dstY) { }
+}