#794 Deduplicate getAccountFull calls in profile page

Use React cache() to deduplicate getAccountFull calls between
generateMetadata and Layout prefetch within the same request.

- Add cached-api.ts with getAccountFullCached wrapper
- Update profile layout to use cached version in both places

This eliminates duplicate API calls for the same user data.

🤖 Generated with [Claude Code](https://claude.com/claude-code

)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>