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>

deploy/backups/backup.sh

@@ -0,0 +1,58 @@
+#!/bin/sh
+# Nightly pg_dump for famapp-db and authentik-db.
+# Called by crond. Outputs to /backups/<db>/daily/<YYYY-MM-DD>.dump
+# and copies into weekly/ (Sundays) and monthly/ (1st of month).
+set -eu
+
+TODAY=$(date +%Y-%m-%d)
+DOW=$(date +%u)  # 1=Mon … 7=Sun
+DOM=$(date +%d | sed 's/^0*//')  # day-of-month without leading zero
+
+dump_db() {
+    local name="$1"
+    local host="$2"
+    local port="$3"
+    local user="$4"
+    local pass="$5"
+    local dbname="$6"
+
+    local daily_dir="/backups/$name/daily"
+    local dest="$daily_dir/$TODAY.dump"
+
+    mkdir -p "$daily_dir" \
+        "/backups/$name/weekly" \
+        "/backups/$name/monthly"
+
+    echo "[backup] dumping $name ..."
+    PGPASSWORD="$pass" pg_dump \
+        -h "$host" -p "$port" -U "$user" -d "$dbname" \
+        -Fc -f "$dest"
+    echo "[backup] $name → $dest"
+
+    if [ "$DOW" = "7" ]; then
+        cp "$dest" "/backups/$name/weekly/$TODAY.dump"
+        echo "[backup] weekly copy saved for $name"
+    fi
+
+    if [ "$DOM" = "1" ]; then
+        cp "$dest" "/backups/$name/monthly/$TODAY.dump"
+        echo "[backup] monthly copy saved for $name"
+    fi
+}
+
+dump_db famapp \
+    "${FAMAPP_DB_HOST:-famapp-db}" \
+    "${FAMAPP_DB_PORT:-5432}" \
+    "$FAMAPP_DB_USER" \
+    "$FAMAPP_DB_PASSWORD" \
+    "$FAMAPP_DB_NAME"
+
+dump_db authentik \
+    "${AUTHENTIK_DB_HOST:-authentik-db}" \
+    "${AUTHENTIK_DB_PORT:-5432}" \
+    "$AUTHENTIK_DB_USER" \
+    "$AUTHENTIK_DB_PASSWORD" \
+    "$AUTHENTIK_DB_NAME"
+
+/scripts/retain.sh
+echo "[backup] complete"