chore(hardening): maintenance jobs, defense-in-depth, redis-backed public rate limit

- maintenance worker now expires GDPR export bundles (db row + MinIO object)
  on the gdpr_exports.expires_at boundary, plus 90-day retention sweep on
  ai_usage_ledger; both jobs scheduled daily.
- portId scoping added to listClientRelationships and listClientExports
  (defense-in-depth — parent-resource gates already prevent cross-tenant
  reads, but service layer should enforce on its own).
- SELECT FOR UPDATE on parent client/company row inside add/update address
  transactions to serialize concurrent isPrimary toggles.
- public /interests + /residential-inquiries endpoints swap their
  in-memory ipHits maps for the redis sliding-window limiter via the
  new rateLimiters.publicForm config (5/hr/IP), so the cap survives
  restarts and is shared across worker processes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/rate-limit.ts

@@ -83,6 +83,8 @@ export const rateLimiters = {
   ai: { windowMs: 60 * 1000, max: 60, keyPrefix: 'ai' },
   /** Data exports (GDPR bundle, PDF, CSV): 30 per hour per user. */
   exports: { windowMs: 60 * 60 * 1000, max: 30, keyPrefix: 'export' },
+  /** Public unauthenticated form posts (interest, residential inquiry): 5 per hour per IP. */
+  publicForm: { windowMs: 60 * 60 * 1000, max: 5, keyPrefix: 'publicform' },
 } as const satisfies Record<string, RateLimitConfig>;
 
 export type RateLimiterName = keyof typeof rateLimiters;