Stage 15 — PWA complete: install prompt + Web Push notifications

Dependency:
- minishlink/web-push v10 (VAPID JWT + aes128gcm payload encryption)
- Dockerfile: add curl, mbstring, gmp extensions (web-push needs ext-curl)

VAPID:
- config/webpush.php from env; `php artisan push:vapid` generates keypair
- Shared platform keypair; .env.example has empty placeholders

Schema:
- push_subscriptions (user/company, endpoint unique, p256dh, auth, encoding)

WebPushService:
- send / sendToUser / dispatch via WebPush::flush
- Auto-prunes subscriptions reported expired (404/410)

Subscribe flow:
- POST /push/subscribe + /push/unsubscribe (auth, tenant)
- Tenant panel JS subscribes after SW registration with VAPID public key

Service worker (/sw.js):
- Cache v2, push listener → showNotification, notificationclick → focus/open

Install prompt:
- Floating "Instalează aplicația" button wired to beforeinstallprompt

Staff push:
- WorkOrder master_id change → push to assigned mechanic
- Settings "Test notificare push" action

Tests (6 new):
- subscribe stores + upserts; requires auth (401); validation (422);
  service configured; sendToUser with no subs returns zero

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

phpunit.xml

@@ -33,5 +33,8 @@
         <env name="TELESCOPE_ENABLED" value="false"/>
         <env name="NIGHTWATCH_ENABLED" value="false"/>
         <env name="CENTRAL_DOMAIN" value="service.mir.md"/>
+        <env name="VAPID_SUBJECT" value="mailto:test@service.mir.md"/>
+        <env name="VAPID_PUBLIC_KEY" value="BKWzp08jgvPShDAn9ND2RZZUviZi8OzSiQqEZGyxKbHwpRXRgDsqNYIk-iQzAOdMHYWjt9tS_9f-Nud5xMBu0YA"/>
+        <env name="VAPID_PRIVATE_KEY" value="F4FtgCigYXyi4C1fEa4a5_D2WUQM2ndwyByL-0FKqQg"/>
     </php>
 </phpunit>