Feat: Creators profile

[cristianFleita]

Closes #19

Summary

Builds the public creator profile page at /creators/[handle], giving fans a responsive pre-subscription view with creator identity, bio, subscriber count, category, subscribe CTA, and posts preview/placeholder support.

Changes

• Added dynamic creator route with generateMetadata and 404 handling for unknown handles.
• Added ProfileHeader with stable banner/avatar layout, category badge, bio, handle, display name, and subscriber count.
• Added SubscribeButton behavior:
  • guests see a login CTA with redirect
  • logged-in fans can subscribe
  • creators viewing their own profile see a disabled “Your profile” state
• Added lib/api/creators.ts with API fetch support and mock fallback data.
• Added creator profile/subscription-related API types.
• Added focused Node tests for mock lookup, API URL fetch behavior, fallback behavior, and unknown handles.
• Added missing react-hook-form root dependency so existing auth forms typecheck correctly.

Testing

• node --test src/lib/api/creators.test.mjs
• tsc --noEmit
• next build
• Smoke-tested:
  • /creators/luna returns 200
  • /creators/unknown-creator returns 404

Results