Initial commit: ANOUMA website with Payload CMS, WebRTC meetings, and booking system

- Next.js 16 App Router site with the ANOUMA design system
- Payload CMS (PostgreSQL) for offers, events, posts and page content
- WebRTC video-call system with custom signaling server
- SMTP email reminders and booking-request notifications
- Customer accounts, calendar-based availability, and booking workflow

lib/booking/lock.ts

@@ -0,0 +1,25 @@
+import { sql } from "drizzle-orm";
+import type { PayloadRequest } from "payload";
+
+/**
+ * Acquires a Postgres transaction-scoped advisory lock so that two
+ * concurrent requests confirming a booking for the same day can't both pass
+ * the "is this slot free?" check before either has committed (Payload's
+ * default transaction isolation is READ COMMITTED, which alone would allow
+ * that race). The lock is automatically released when the transaction ends.
+ *
+ * Must be called from inside a Payload hook/operation that already has an
+ * active `req.transactionID` (true for collection create/update by default).
+ */
+export async function acquireBookingDayLock(req: PayloadRequest, dateKey: string): Promise<void> {
+  const txID = req.transactionID ? String(await req.transactionID) : undefined;
+  if (!txID) return; // No active transaction — nothing to lock against.
+
+  const adapter = req.payload.db as unknown as {
+    sessions?: Record<string, { db: { execute: (query: unknown) => Promise<unknown> } }>;
+    drizzle: { execute: (query: unknown) => Promise<unknown> };
+  };
+  const tx = adapter.sessions?.[txID]?.db ?? adapter.drizzle;
+
+  await tx.execute(sql`SELECT pg_advisory_xact_lock(hashtext(${dateKey}))`);
+}