refactor: remove voice, recording, and music/media features (gateway + backend)

- Gateway: delete voice-recording/, voice-pcm-ws/, voice/video/media handlers,
  vendor/discord-voice-fork/, voice DB repos, 2 voice migrations
- Gateway: cut voice wiring from bootstrap/shutdown/commandHandler/handler-registry,
  eventBroadcaster/eventTypes, redis-channels, moderation-types, message-capture,
  config keys, and deps (@discordjs/voice, opus, libsodium, prism-media, davey)
- Backend: delete voice/, recordings/, media/ modules + @discordjs/voice dep
- Backend: cut voice/media/recordings oRPC routers, WS gateway-PCM auth + voice
  handlers, Redis bridge voice aggregation, redis-channels voice/media constants,
  config keys, moderation-types voice items, e2e voice/recordings suites
- Keep voice DB tables (destructive migration avoided); chatbot voiceRecordings
  tool + dashboard count remain as read-only historical data access

services/backend/src/e2e.test.ts

@@ -41,20 +41,6 @@ describe("API Dashboard", () => {
   });
 });
 
-describe("API Recordings", () => {
-  it("GET /recordings returns items with pagination", async () => {
-    const { status, body } = await api("/recordings?limit=5");
-    expect(status).toBe(200);
-    expect(body).toHaveProperty("items");
-    expect(Array.isArray(body.items)).toBe(true);
-    if (body.items.length > 0) {
-      expect(body.items[0]).toHaveProperty("id");
-      expect(body.items[0]).toHaveProperty("username");
-      expect(body.items[0]).toHaveProperty("created_at");
-    }
-  });
-});
-
 describe("API Config", () => {
   it("GET /config returns 200", async () => {
     const { status } = await api("/config");
@@ -62,13 +48,6 @@ describe("API Config", () => {
   });
 });
 
-describe("API Voice", () => {
-  it("GET /guilds returns 200", async () => {
-    const { status } = await api("/guilds");
-    expect(status).toBe(200);
-  });
-});
-
 describe("API Negative", () => {
   it("GET /nonexistent returns 404", async () => {
     const { status } = await api("/nonexistent");