Add roving focus and arrow-key navigation to the notification dropdown

[Austinaminu2]

Description

Opening the notification dropdown in `components/layout/notification-bell.tsx:88-124` doesn't move focus into it, and there's no way to arrow through notification items — only Escape (which returns focus to the trigger) is currently handled.

Location

`components/layout/notification-bell.tsx:88-124`

Task

On open, move focus to the first notification item (or the panel itself), and add Up/Down arrow-key navigation between notification items, following standard menu/listbox keyboard patterns.

Good for contributors because

Well-defined keyboard interaction pattern (common in menu/dropdown components) with existing examples to reference from accessibility guidelines.

[Peolite001]

I would love to work on this issue

[gloskull]

@gloskull has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi, I’d love to work on this issue. I have 4 years of experience across backend, frontend, full-stack, and smart contract development. I understand the task clearly and can deliver a clean, efficient, well-tested solution on time, with strong focus on code quality and maintainability. My PR will be submitted in 8hours.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @gloskull to this issue.

[Joel234-png]

@Joel234-png has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hey maintainer, I'd like to show you what am capable of doing. Kindly assign this to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Joel234-png to this issue.

[drips-wave]

Congratulations, @Joel234-png! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @Joel234-png: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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