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>

src/core/graph/nodes/action/PlaySound.ts

@@ -1,6 +1,6 @@
 import type { NodeDef, PortDef } from '../../NodeRegistry';
 import { asBoolean, asNumber, asString, type Value } from '../../values';
-import { exec, num, soundPort, withDefault } from '../shared';
+import { exec, num, soundFxPort, soundPort, withDefault } from '../shared';
 
 /**
  * Three answers, not two: a checkbox cannot say "leave it to the asset", and without that a sound
@@ -56,14 +56,20 @@ export const PlaySound: NodeDef = {
     "leaves the asset's own setting alone or overrules it, so the asset says what the sound is and " +
     'the node only colors it. Each play is a voice of its own: firing this twice in a row is heard ' +
     'twice, overlapping. The sound belongs to this object and stops when the object is destroyed, ' +
-    'unless "detached" is on.',
-  inputs: [exec(), soundPort(), withDefault(num('volume'), 1), loopPort(), detachedPort()],
+    'unless "detached" is on. "fx" sends it through a sound FX asset; left empty, it plays as it is.',
+  inputs: [exec(), soundPort(), withDefault(num('volume'), 1), loopPort(), detachedPort(), soundFxPort()],
   outputs: [exec()],
   params: [],
   run: (ctx, inputs) => {
     const sound = asString(inputs.sound);
     if (sound)
-      ctx.playSound(sound, asNumber(inputs.volume), loopChoice(inputs.loop), asBoolean(inputs.detached));
+      ctx.playSound(
+        sound,
+        asNumber(inputs.volume),
+        loopChoice(inputs.loop),
+        asBoolean(inputs.detached),
+        asString(inputs.fx),
+      );
     return { next: 'exec' };
   },
 };

src/core/graph/nodes/index.ts

@@ -146,6 +146,7 @@ import { StateTransition } from './flow/StateTransition';
 import { PARTICLE_NODES } from '../../particles/nodes';
 import { SHADER_FUNCTION_NODES } from '../../shader/functions';
 import { SHADER_NODES } from '../../shader/nodes';
+import { SOUND_FX_NODES } from '../../soundfx/nodes';
 import { State } from '../stateMachine';
 import { Variables } from './variable/Variables';
 
@@ -314,3 +315,4 @@ registerNode(State);
 for (const def of SHADER_NODES) registerNode(def);
 for (const def of SHADER_FUNCTION_NODES) registerNode(def);
 for (const def of PARTICLE_NODES) registerNode(def);
+for (const def of SOUND_FX_NODES) registerNode(def);

src/core/graph/nodes/shared.ts

@@ -94,6 +94,14 @@ export const soundPort = (): PortDef => ({
   field: { key: 'sound', label: 'Sound', kind: 'sound', default: '' },
 });
 
+/** The `fx` input of `Play sound` (#311); unconnected, it shows the picker of sound FX assets. */
+export const soundFxPort = (): PortDef => ({
+  key: 'fx',
+  label: 'fx',
+  type: 'string',
+  field: { key: 'fx', label: 'FX', kind: 'asset', default: '', assetTypes: ['soundfx'] },
+});
+
 export function binaryMath(type: string, description: string, fn: (a: number, b: number) => number): NodeDef {
   return {
     type,