[US-022] In-app notification center

[leimo2011]

User Story

As a user,
I want an in-app notification center to view all my past notifications,
So that I don't miss anything even if I dismissed push notifications.

Acceptance Criteria

• Bell icon in app nav bar with unread badge count
• Notification list shows: icon, title, body, timestamp, read/unread status
• Mark all as read action
• Tapping notification navigates to relevant screen
• Notifications paginated (load more on scroll)
• Notifications retained for 30 days

Estimate: 3 SP | Milestone: M3

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Epic: [EPIC-09] Notifications System