feat: migrate app to local Fastify and Postgres stack

Replace Supabase auth and search runtime with a local Fastify API, PostgreSQL/PostGIS schema, and local session handling. Scaffold the worker and deep-research foundations while keeping the existing research, dashboard, and map flows running on the new backend.

server/src/app.ts

@@ -0,0 +1,30 @@
+import Fastify from 'fastify';
+import cookie from '@fastify/cookie';
+import cors from '@fastify/cors';
+import { getEnv } from './config/env.js';
+import { authRoutes } from './routes/auth.js';
+import { healthRoutes } from './routes/health.js';
+import { searchJobRoutes } from './routes/search-jobs.js';
+
+export async function buildApp() {
+  const env = getEnv();
+  const app = Fastify({
+    logger: true,
+  });
+
+  await app.register(cors, {
+    origin: env.APP_ORIGIN,
+    credentials: true,
+  });
+
+  await app.register(cookie, {
+    secret: env.COOKIE_SECRET,
+    hook: 'onRequest',
+  });
+
+  await app.register(healthRoutes, { prefix: '/api' });
+  await app.register(authRoutes, { prefix: '/api' });
+  await app.register(searchJobRoutes, { prefix: '/api' });
+
+  return app;
+}