Skip fetchAgentSkills for www typecheck GHA (#47907)

### Context

Our TS check GHA occasionally runs into GH rate limits because of
`fetchAgentSkills`

### Changes involved
- Opting to omit `fetchAgentSkills` for typecheck
  - `generateStaticContent` is needed still afaict
- Allow GITHUB_TOKEN to be passed for `generateStaticContent`
  - And pass that env var from `typecheck.yml`



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## Summary by CodeRabbit

- **Improvements**
  - Enhanced reliability of GitHub-powered content during site builds.
- GitHub API requests now use secure authentication when a token is
available, improving consistency and reducing rate-limit risk.
- Repository star and agent-skill loading continues to work gracefully
without token access.

- **Chores**
- Streamlined the type-check workflow to use a leaner content build
before running TypeScript checks.
- Passed the GitHub token through relevant CI task environments to
enable authenticated requests.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

apps/www/scripts/generateStaticContent.mjs

@@ -237,7 +237,7 @@ let stars = 0
 // GitHub Stars
 const fetchOctoData = async () => {
   const { Octokit } = await import('@octokit/core')
-  const octokit = new Octokit()
+  const octokit = new Octokit(process.env.GITHUB_TOKEN ? { auth: process.env.GITHUB_TOKEN } : {})
   const res = await octokit.request('GET /repos/{org}/{repo}', {
     org: 'supabase',
     repo: 'supabase',