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>

src/modules/_core/push.ts

@@ -1,6 +1,7 @@
 import webPush from "web-push";
 import { and, eq, inArray } from "drizzle-orm";
 import { db } from "@/lib/db";
+import logger from "@/lib/logger";
 import { pushSubscriptions } from "./schema";
 
 function ensureVapidConfigured() {
@@ -40,7 +41,7 @@ export async function sendPush(
         if (status === 404 || status === 410) {
           staleIds.push(sub.id);
         } else {
-          console.error("[famapp] push delivery failed:", err);
+          logger.error({ err }, "push delivery failed");
         }
       }
     }),