feat(backend): add fastify api, auth, prisma schema and jobs

apps/backend/src/auth/users.registry.ts

@@ -0,0 +1,30 @@
+import { resolveUsers } from '../config/env.js';
+import type { RegistryUser } from './users.registry.types.js';
+
+// Built once on process start from env. Source of truth for credentials.
+// DB contains only "public" copies (id, username, slug, displayName) — never the hash.
+const users: RegistryUser[] = resolveUsers();
+const byUsername = new Map(users.map((u) => [u.username, u] as const));
+const byId = new Map(users.map((u) => [u.id, u] as const));
+
+export const usersRegistry = {
+  all(): readonly RegistryUser[] {
+    return users;
+  },
+  findByUsername(username: string): RegistryUser | undefined {
+    return byUsername.get(username);
+  },
+  findById(id: string): RegistryUser | undefined {
+    return byId.get(id);
+  },
+};
+
+// Pre-computed bcrypt hash of a random string, used for timing-safe compare
+// when the requested username does not exist. Generated lazily on first need.
+let dummyHashCache: string | null = null;
+export async function getDummyHash(): Promise<string> {
+  if (dummyHashCache) return dummyHashCache;
+  const { default: bcrypt } = await import('bcryptjs');
+  dummyHashCache = await bcrypt.hash('__not_a_real_password__', 10);
+  return dummyHashCache;
+}