[Frontend] Offline credential wallet with local verification

[Penielka]

Overview

Learners should access and verify their credentials offline. Build a client-side wallet that stores credentials locally, verifies signatures locally, and syncs when back online.

Acceptance Criteria

• Credentials stored and displayed offline
• Local signature verification without a server round-trip
• Sync with on-chain state when connectivity returns
• Tamper-evident storage for local credentials
• Export/import of the wallet (backup and restore)

Files to Modify

• frontend/src/lib/wallet/ — local credential wallet
• frontend/src/components/wallet/ — wallet UI
• frontend/src/utils/offlineDB.ts — storage layer
• backend/src/routes/credentials/sync.ts — sync endpoint

Priority: Medium

[Chigybillionz]

Hi, I’ve reviewed this issue and I’m confident I can fix it. I’d like to take it on.

[grantfox-oss]

🦊 GrantFox — @Chigybillionz has been assigned to this issue as part of the Third Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #398)
2. Your PR will be reviewed by the AetherEdu maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@Chigybillionz's PR #487 was approved and merged by @Penielka.

🏆 @Chigybillionz: You earned 40 FoxPoints for this contribution! Your current tier: Builder (2,915 total points). Track your full progress on GrantFox.

👏 Great work, @Chigybillionz! Keep contributing to AetherEdu.