Play a sound through a graph of gain, pitch and EQ effects #311

A sound could only be played as it was uploaded. A Sound FX asset is
a node graph like a shader: Input, effects, Output. Play sound has a
new input fx that sends the voice through it.

- New asset type soundfx ("Sound FX"), not placeable, with a graph
  and its own tab. The heading in the asset panel is "Sound effects",
  so it does not take the click meant for the + menu entry.
- Nodes in core/soundfx/nodes.ts, category sound, port type audio
  that only fits audio: Input, Output, Gain (dB), Pitch (semitones),
  EQ (80 Hz and 12 kHz shelves, peaks at 250 Hz, 1 kHz and 4 kHz).
- compileSoundFx walks back from the Output with the shared graph
  emitter. An input takes one edge, so the result is one line: a
  pitch and a list of gain and filter stages. A node without input
  or a graph without Output reports a problem on the node.
- Pitch is the playback rate of the source. It applies to the whole
  sound and also changes its length, the node description says so.
- The BehaviorSystem resolves fx and hands the line to the AudioSink.
  An fx that is missing or does not compile plays the sound dry.
- SoundLibrary wires source, stages, volume, destination in that
  order. stats().last now also names pitch and stage count.
- The tab header picks one of the project's sounds and plays it
  through the graph as it stands. Stop there ends only its own voice.

Tests:
- soundfx.test.ts (new, 11), sound-library (9, +2 for the wiring),
  node-catalog (+1 for fx), graph and asset-groups adjusted
- e2e 34: ALL PASSED - 26 checks (+5: + menu opens the tab, palette,
  2 effects, tab Play and game Play through the FX at -12 st)
- Gate on melektaus-atx: typecheck, lint, prettier clean, 239 of 240
  test files green. The red one was sound-library (its fake
  AudioContext had no playbackRate), fixed afterwards, gate not
  re-run in full.
- Counter-check: without the audio rule in portsCompatible the port
  test fails.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/core/graph.test.ts

@@ -79,8 +79,10 @@ describe('node registry', () => {
       if (def.category === 'event') expect(def.inputs.filter((p) => p.type === 'exec')).toHaveLength(0);
       // A state is a name in a machine; its ports only anchor transitions, so it never runs.
       else if (def.category === 'state') expect(def.run).toBeUndefined();
-      // A shader node is compiled to GLSL and a particle node to a function: neither is ever run.
-      else if (def.category === 'shader' || def.category === 'particles') expect('emit' in def).toBe(true);
+      // A shader node is compiled to GLSL, a particle node to a function and a sound FX node to a
+      // stage of a voice: none is ever run.
+      else if (def.category === 'shader' || def.category === 'particles' || def.category === 'sound')
+        expect('emit' in def).toBe(true);
       // The end of a block runs as part of the node that opens it (`Find` … `Match`).
       else if (defs.some((d) => d.opens?.type === def.type)) expect(def.run).toBeUndefined();
       // Everything else does one of the two: a step (`run`), or an answer whenever asked (`read`).