feat: web push notifications, mobile-ready (PRD §5.6)

ADR 0003: VAPID self-hosted today, DeviceToken model agnostic to
platform so iOS/Android (Expo/APNs/FCM) plug in as new senders later.

Backend (apps/api/src/modules/notifications)
- sender.ts: NotificationSender interface, WebPushSender via VAPID
- notifications.routes.ts: GET /me/notifications/config, POST/DELETE
  /me/device-tokens, PATCH /me/notifications/settings, POST /me/notifications/test
- scheduler.ts: node-cron Mon 09:00 Europe/Rome for weekly weigh-in
  reminder; auto-cleanup of expired tokens on 404/410
- env: VAPID_PUBLIC_KEY/PRIVATE_KEY/SUBJECT (all optional → push gracefully off)

Frontend
- public/sw.js minimal (push + notificationclick)
- lib/notifications/push-client.ts: subscribe / unsubscribe / getCurrentSubscription
- profile/notifications-{actions,panel}.tsx: editorial panel with toggles,
  device list, "send test", per-device removal
- pushReady requires both permission AND active subscription (covers the
  case where the user revoked the SW but kept the browser permission)

Schema
- DeviceToken { userId, platform, endpoint, p256dh, auth, token, userAgent,
  createdAt, lastSeenAt } with unique(userId, endpoint)
- ExtendedPrismaClient type exported from @ketopath/db
- NotificationSettings zod schema in @ketopath/shared

Tooling
- lint-staged: split .js out of eslint glob so service worker is only
  formatted (it lives outside the TS project)

i18n
- Notifications namespace (it) with typed error keys

Smoke tested: POST /me/device-tokens 201, POST /me/notifications/test 200,
real push delivered to a macOS Chrome device.

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

apps/api/.env.example

@@ -23,3 +23,11 @@ BETTER_AUTH_URL=http://localhost:3000
 
 # Sentry — error tracking (lascia vuoto per disabilitare)
 # SENTRY_DSN=
+
+# Web Push — VAPID (vedi ADR 0003).
+# Genera con: cd apps/api && node -e "console.log(require('web-push').generateVAPIDKeys())"
+# La PUBLIC_KEY va anche in apps/web/.env come NEXT_PUBLIC_VAPID_PUBLIC_KEY.
+# Lascia vuoto per disabilitare le push (il cron e gli endpoint rispondono 503).
+VAPID_PUBLIC_KEY=
+VAPID_PRIVATE_KEY=
+VAPID_SUBJECT=mailto:hello@ketopath.app