voice: audit + noise suppression toggle + stability fixes

Gateway:
- transmitter.ts: cap backpressure queue at 500 chunks (prevents memory leak)
- transmitter.ts: fix Redis race — assign redisSub AFTER subscribe completes
- voice.handler.ts: static import Redis instead of dynamic (cleaner, no eval)

Frontend:
- mic-transmit.ts: MicAccessError with specific reasons (permission-denied, no-mic, timeout)
- mic-transmit.ts: noiseSuppression option in getUserMedia constraints
- mic-transmit.ts: proper DOMException handling for all getUserMedia failure modes
- use-voice.ts: noiseSuppression state + toggleNoiseSuppression exposed
- use-voice.ts: cleanup on unmount (stops transmitter, clears refs)
- voice/view.tsx: noise suppression toggle button (ShieldCheck/ShieldOff icons)
- voice/view.tsx: improved mic error toasts (permission denied / no mic specific)
- voice/view.tsx: NS status in codec footer (NS_ACTIVE when enabled)

services/discord-gateway/src/modules/command-handler/voice.handler.ts

@@ -1,4 +1,5 @@
 import type { Client } from "discord.js-selfbot-v13";
+import Redis from "ioredis";
 import { config } from "../../shared/config/config.js";
 import type { CommandMessage, CommandReply } from "../../shared/index.js";
 import { createChildLogger } from "../../shared/logger/index.js";
@@ -157,8 +158,7 @@ export class VoiceHandler {
       // .subscribe() which converts the connection to subscriber mode.  Reusing
       // the publish connection from CommandHandler would corrupt it and break
       // every command reply + status update.
-      const { default: IORedis } = await import("ioredis");
-      const transmitRedis = new IORedis(config.REDIS_URL);
+      const transmitRedis = new Redis(config.REDIS_URL);
       await voiceTransmitter.start(transmitRedis);
 
       const status = voiceTransmitter.getStatus();