feat(security): share rate limits across instances, drain syncs on shutdown

- Rate limiting counters live in PostgreSQL (throttler_records), shared by
  every instance, one atomic upsert per request; fails open.
- On shutdown, new syncs are refused (503) and the running one is waited for
  up to SYNC_SHUTDOWN_TIMEOUT; Prisma disconnects last.
- Hiboutik calls never follow redirects and are capped at 50 MB.
- Prisma errors no longer print query arguments (errorFormat minimal).
- In production, DATABASE_URL must require TLS.
- The sync lock connection times out after 10 s.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/app.e2e-spec.ts

@@ -10,14 +10,18 @@ import { PrismaService } from './../prisma/prisma.service';
 describe('AppController (e2e)', () => {
   let app: INestApplication<App>;
   const hiboutikService = { startSync: jest.fn() };
+  // Rate limiting counters (ThrottlerDatabaseStorage): the database answers "not blocked" unless a test says otherwise
+  const notBlocked = { totalHits: 1, timeToExpire: 60, isBlocked: false, timeToBlockExpire: 0 };
+  const prisma = { $queryRaw: jest.fn(), throttlerRecord: { deleteMany: jest.fn().mockResolvedValue({ count: 0 }) } };
 
   beforeEach(async () => {
     hiboutikService.startSync.mockReset();
+    prisma.$queryRaw.mockReset().mockResolvedValue([notBlocked]);
     const moduleFixture: TestingModule = await Test.createTestingModule({
       imports: [AppModule],
     })
       .overrideProvider(PrismaService)
-      .useValue({})
+      .useValue(prisma)
       .overrideProvider(HiboutikService)
       .useValue(hiboutikService)
       .compile();
@@ -36,6 +40,13 @@ describe('AppController (e2e)', () => {
     return request(app.getHttpServer()).post('/sync').expect(409);
   });
 
+  it('POST /sync answers 429 when the shared rate limiting counter is blocked', async () => {
+    prisma.$queryRaw.mockResolvedValue([{ totalHits: 6, timeToExpire: 30, isBlocked: true, timeToBlockExpire: 30 }]);
+
+    await request(app.getHttpServer()).post('/sync').expect(429).expect('Retry-After', '30');
+    expect(hiboutikService.startSync).not.toHaveBeenCalled();
+  });
+
   afterEach(async () => {
     await app.close();
   });