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/ui-state/ui-state.routes.ts

@@ -0,0 +1,34 @@
+import type { Request, Response, Router } from "express";
+import express from "express";
+import { createChildLogger } from "../../shared/logger/index.js";
+import { asyncHandler } from "../../shared/middlewares/index.js";
+import { uiStateService } from "./ui-state.service.js";
+
+const logger = createChildLogger("ui-state.routes");
+
+export function createUiStateRouter(): Router {
+  const router = express.Router();
+
+  // GET /api/ui-state
+  router.get(
+    "/ui-state",
+    asyncHandler(async (_req: Request, res: Response) => {
+      logger.debug("Fetching UI state");
+      const state = await uiStateService.getState();
+      res.json(state);
+    }),
+  );
+
+  // POST /api/ui-state
+  router.post(
+    "/ui-state",
+    asyncHandler(async (req: Request, res: Response) => {
+      const updates = req.body as Record<string, unknown>;
+      logger.debug({ keys: Object.keys(updates) }, "Updating UI state");
+      const result = await uiStateService.updateState(updates);
+      res.json(result);
+    }),
+  );
+
+  return router;
+}