feat: add transient suppressor to audio pipeline

Implements a per-sample transient suppressor in the noise gate AudioWorklet
that instantly cuts gain when a sudden loud peak (desk hit, mic bump) exceeds
the slow background RMS by a configurable threshold, then releases over a
short window. Exposes enable, sensitivity, and release controls in the audio
settings tab.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/state/CallViewModel/localMember/Publisher.ts

@@ -38,6 +38,9 @@ import {
   noiseGateAttack,
   noiseGateHold,
   noiseGateRelease,
+  transientSuppressorEnabled,
+  transientThreshold,
+  transientRelease,
 } from "../../../settings/settings.ts";
 import {
   type NoiseGateParams,
@@ -438,6 +441,9 @@ export class Publisher {
       attackMs: noiseGateAttack.getValue(),
       holdMs: noiseGateHold.getValue(),
       releaseMs: noiseGateRelease.getValue(),
+      transientEnabled: transientSuppressorEnabled.getValue(),
+      transientThresholdDb: transientThreshold.getValue(),
+      transientReleaseMs: transientRelease.getValue(),
     });
 
     // Attach / detach processor when enabled state or the track changes.
@@ -482,10 +488,17 @@ export class Publisher {
       noiseGateAttack.value$,
       noiseGateHold.value$,
       noiseGateRelease.value$,
+      transientSuppressorEnabled.value$,
+      transientThreshold.value$,
+      transientRelease.value$,
     ])
       .pipe(scope.bind())
-      .subscribe(([threshold, attackMs, holdMs, releaseMs]) => {
-        transformer?.updateParams({ threshold, attackMs, holdMs, releaseMs });
+      .subscribe(([threshold, attackMs, holdMs, releaseMs,
+                   transientEnabled, transientThresholdDb, transientReleaseMs]) => {
+        transformer?.updateParams({
+          threshold, attackMs, holdMs, releaseMs,
+          transientEnabled, transientThresholdDb, transientReleaseMs,
+        });
       });
   }