implement better-auth auth with postgres and route protection

app/api/filings/sync/route.ts

@@ -1,7 +1,13 @@
 import { asErrorMessage, jsonError } from '@/lib/server/http';
+import { requireAuthenticatedSession } from '@/lib/server/auth-session';
 import { enqueueTask } from '@/lib/server/tasks';
 
 export async function POST(request: Request) {
+  const { session, response } = await requireAuthenticatedSession();
+  if (response) {
+    return response;
+  }
+
   try {
     const payload = await request.json() as {
       ticker?: string;
@@ -13,6 +19,7 @@ export async function POST(request: Request) {
     }
 
     const task = await enqueueTask({
+      userId: session.user.id,
       taskType: 'sync_filings',
       payload: {
         ticker: payload.ticker.trim().toUpperCase(),