Implement tasks 60, 61, 62: backups, rate limiting, structured logging

Task 60 — Postgres backups:
- deploy/backups/: backup.sh (pg_dump -Fc nightly), retain.sh (14/8/6 tiers),
  restore.sh, entrypoint.sh, crontab
- famapp-backup Alpine service + backups volume added to deploy/compose.yaml
- Restore procedure in deploy/backups/README.md

Task 61 — Rate limiting on share links:
- src/lib/rate-limit.ts: Edge-compatible sliding-window counter (50/min, LRU eviction)
  with consume(), isRateLimited(), recordFailure() exports
- middleware.ts: enforces 429 with Retry-After: 60 for /s/[token] (IP + token prefix)
- /s/[token]/page.tsx: tracks only failed resolveShareToken calls via recordFailure()

Task 62 — Structured logging:
- pino + pino-pretty installed; serverExternalPackages added to next.config.ts
- src/lib/logger.ts: JSON in production, pretty in dev, level from LOG_LEVEL env
- middleware.ts: structured JSON request log (method, path, status, ms, authenticated)
- _core/push.ts, notify.ts, reminders.ts: console.error/log → logger.error/info

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -38,6 +38,7 @@
     "eslint": "^9.15.0",
     "eslint-config-next": "^16.2.4",
     "globals": "^15.12.0",
+    "pino-pretty": "^13.1.3",
     "prettier": "^3.3.3",
     "tailwindcss": "^4.2.4",
     "tsx": "^4.19.4",
@@ -59,6 +60,7 @@
     "lucide-react": "^1.14.0",
     "next": "^15.5.15",
     "next-auth": "5.0.0-beta.31",
+    "pino": "^10.3.1",
     "postgres": "^3.4.9",
     "react": "^19.2.5",
     "react-dom": "^19.2.5",