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>

prisma/schema.prisma

@@ -130,7 +130,7 @@ model Customer {
   updatedAt DateTime @updatedAt
 
   dateOfBirth       DateTime?
-  /// Kept when removed in Hiboutik (an empty Hiboutik email does not erase it)
+  /// Null when the customer has no email in Hiboutik (erased when removed there)
   email             String?
   firstName         String
   hiboutikId        Int       @unique
@@ -227,3 +227,19 @@ model OrderLine {
 
   @@map("order_lines")
 }
+
+/// Rate limiting counter shared by every instance (ThrottlerDatabaseStorage): one fixed window per throttler key
+/// (route + client IP). Not synced from Hiboutik. Rows whose window and block are over are purged regularly.
+model ThrottlerRecord {
+  /// Key generated by the ThrottlerGuard (hash of route, throttler name and client IP)
+  key          String    @id
+  /// Requests counted in the current window
+  hits         Int
+  /// End of the current window
+  expiresAt    DateTime  @db.Timestamptz(3)
+  /// End of the block once the limit was exceeded, null when not blocked
+  blockedUntil DateTime? @db.Timestamptz(3)
+
+  @@index([expiresAt])
+  @@map("throttler_records")
+}