Build invoice notification center

[Kingsman-99]

Label: complexity: high
Points: 200

Description

There is no central place to see all recent invoice activity. This issue adds a notification bell icon in the header that opens a dropdown showing all recent events (payments received, invoices funded, invoices released) stored in localStorage, with unread count badge and mark-all-read functionality.

Technical Context

Involves a new src/components/NotificationCenter.tsx added to layout.tsx. Notifications are written to localStorage by the polling mechanism (Issue 1) when invoice state changes are detected. Each notification has id, type, invoiceId, message, timestamp, and read fields.

Acceptance Criteria

• Bell icon in header shows unread count badge
• Dropdown lists notifications in reverse chronological order
• Unread notifications are visually distinct from read ones
• "Mark all as read" button clears the unread badge
• Clicking a notification navigates to the relevant invoice
• Mobile responsive — works on 375px screens
• No TypeScript errors

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[NnamdiCyber]

@NnamdiCyber has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I can deliver an excellent work on this

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[drips-wave]

Congratulations, @NnamdiCyber! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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[drips-wave]

This issue has been completed by @NnamdiCyber as part of the Stellar Wave Program's 5th Wave 🥳

😎 @NnamdiCyber: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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