feat(backend): implement all missing endpoints, real analytics queries, and WebSocket server

- Replace stub analytics.repository.ts with real PostgreSQL queries using pg.Pool
- Add /api/guilds, /api/config, /api/auth/login, /api/ui-state (GET/POST)
- Add /api/review, /api/recordings, /api/analysis/search
- Add /api/messages/:id/reanalyze endpoint
- Add /api/analytics/heatmap and /api/analytics/topics
- Implement media routes (stub responses, backend has no Discord voice client)
- Add WebSocket server at /ws with heartbeat and broadcast functions
- Fix analytics route paths to match frontend contract (dual paths for backward compat)
- Export getPool() from database module for raw SQL queries
- Register all new routers in app.ts

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/backend/src/modules/voice/voice.controller.ts

@@ -0,0 +1,42 @@
+import type { Request, Response } from "express";
+import {
+  connectVoice,
+  disconnectVoice,
+  getVoiceChannels,
+  getVoiceStatus,
+} from "./voice.service.js";
+
+export async function handleGetVoiceStatus(_req: Request, res: Response) {
+  const status = getVoiceStatus();
+  res.json(status);
+}
+
+export async function handleConnectVoice(req: Request, res: Response) {
+  const guildId = Array.isArray(req.body.guildId)
+    ? req.body.guildId[0]
+    : req.body.guildId;
+  const channelId = Array.isArray(req.body.channelId)
+    ? req.body.channelId[0]
+    : req.body.channelId;
+  if (!guildId || !channelId) {
+    return res.status(400).json({
+      error: "VALIDATION_ERROR",
+      message: "guildId and channelId are required",
+    });
+  }
+  const status = await connectVoice(guildId, channelId);
+  res.json(status);
+}
+
+export async function handleDisconnectVoice(_req: Request, res: Response) {
+  const status = await disconnectVoice();
+  res.json(status);
+}
+
+export async function handleGetVoiceChannels(req: Request, res: Response) {
+  const guildId = Array.isArray(req.params.guildId)
+    ? req.params.guildId[0]
+    : req.params.guildId;
+  const channels = await getVoiceChannels(guildId);
+  res.json(channels);
+}