Fix public profile hydration and local metadata handling for user content

[grantfox-oss]

Reduce hydration drift and metadata inconsistency in public profile rendering so usernames, avatars, and stored user data load predictably across refreshes and slow networks.

• Affected files: app/frontend/src/app/[username]/page.tsx, app/frontend/src/lib/api.ts, app/frontend/src/components/UsernameCard.tsx, app/frontend/src/types/profile.ts, app/frontend/src/app/manifest.ts, app/frontend/src/components/Header.tsx, app/frontend/src/components/SearchBar.tsx, app/frontend/src/app/page.tsx
• Acceptance criteria:
  • Profile pages render stable content without hydration mismatches or flicker.
  • Stored profile metadata is merged safely and recovers gracefully from malformed local data.
  • Empty, private, or invalid profile states display consistent fallback UX and error copy.

[IamOluwatoyin]

I would love to work on this task as it aligns well with my frontend skill, particularly around profile rendering, data handling, and improving the overall user experience.

I would focus on resolving the hydration mismatches and flickering, ensuring stored profile metadata such as usernames and avatars is merged and handled safely, and adding graceful fallbacks for malformed or missing data. I would also ensure that empty, private, and invalid profile states have consistent UX and error messaging, then test the affected flows across refreshes and slower network conditions.

[grantfox-oss]

🦊 GrantFox — @IamOluwatoyin 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 #524)
2. Your PR will be reviewed by the BlockDash-Studios maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@IamOluwatoyin's PR #529 was approved and merged by @MaryammAli.

🏆 @IamOluwatoyin: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (519 total points). Track your full progress on GrantFox.

👏 Great work, @IamOluwatoyin! Keep contributing to BlockDash-Studios.