feat(sprint-6): Phase 6 — Notifications (WebSocket) + PWA

- WebSocket: Spring STOMP + SockJS, NotificationService, persistent notifications table
- NotificationController: GET/PUT endpoints for notification management
- Frontend: notification bell with unread badge, dropdown panel, real-time via STOMP
- PWA: manifest.json, service worker (manual sw.js), offline page, install prompt
- PWA icons (192+512), dark theme colors, standalone display
- Full i18n (de/en) for notifications and PWA
- Flyway V10 migration for notifications table
- spring-boot-starter-websocket dependency added

cannamanage-frontend/e2e/staff-management.spec.ts

@@ -26,7 +26,9 @@ test.describe("Staff Management", () => {
 
     // If redirected to login, that's expected without a running backend
     if (page.url().includes("/login")) {
-      console.log("   ℹ️  Redirected to login (no session) — expected without backend")
+      console.log(
+        "   ℹ️  Redirected to login (no session) — expected without backend"
+      )
       return
     }
 
@@ -53,7 +55,9 @@ test.describe("Staff Management", () => {
 
       // Sheet/dialog should open with form fields
       const hasEmailField =
-        (await page.locator('input[type="email"], input[name="email"]').count()) > 0
+        (await page
+          .locator('input[type="email"], input[name="email"]')
+          .count()) > 0
       expect(hasEmailField).toBe(true)
     }
   })
@@ -69,7 +73,8 @@ test.describe("Staff Management", () => {
 
     // Check for table or list structure
     const hasTable = (await page.locator("table").count()) > 0
-    const hasList = (await page.locator('[role="list"], [data-testid*="staff"]').count()) > 0
+    const hasList =
+      (await page.locator('[role="list"], [data-testid*="staff"]').count()) > 0
 
     expect(hasTable || hasList).toBe(true)
   })