Improve GitHub API diagnostics for project creation failures

[saracarl]

Motivation

• Creating repositories from the shared template was producing opaque 500 errors for enterprise-managed users, making it hard to diagnose whether the issue was token scope, enterprise policy, or template-generation failures.
• We need richer server-side diagnostics (request ids, scopes, rate-limit info, and parsed response payloads) to correlate with GitHub support and to tell permission problems from true server errors.

Description

• Add a reusable logGitHubErrorResponse helper in the project-creation API route (src/pages/api/projects/[projectName]/index.ts) that logs status, x-github-request-id/x-request-id, x-ratelimit-remaining, OAuth scopes, and a safely-parsed response body (JSON or text).
• Use the helper for the critical failure points: repo-create-from-template, pages-enable, and topics-replace, so POST/PATCH failures emit actionable logs.
• Return the upstream GitHub HTTP status (or fallback to 500) and preserve statusText for these failure responses instead of always coercing to 500.
• The change makes it easier to trace enterprise-specific failures and shows where additional logging (for example in src/lib/GitHub/index.ts before fetch) would be helpful.

Testing

• Ran npm run build (which runs astro check && astro build) and the build completed successfully with TypeScript warnings only.
• Verified the modified file is type-checking as part of the build step and the server bundle was produced successfully.

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Codex Task

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