Show source repository on book metadata page

[averyquinnhq]

Summary

• show the configured GitHub repository on the book metadata edit page
• keep the repository value read-only and show a clear fallback when none is recorded
• add rendering coverage for both cases

Tests

• pytest -q test/components/rsptx/templates/test_core.py — 3 passed in an isolated environment matching the declared FastAPI 0.115 range
• ruff check bases/rsptx/author_server_api/main.py test/components/rsptx/templates/test_core.py
• ruff format --check bases/rsptx/author_server_api/main.py test/components/rsptx/templates/test_core.py

Closes #732

AI-assisted contribution prepared and tested by Avery Quinn, working with @vivid0o0.

[bnmnetp]

Thanks! I merged this with one small change. I moved the repo information to below all the editable data.

The only other minor improvement might be to make the repo URL clickable so that it is easy to visit. But since it already belongs to the author that seems super low priority.

[averyquinnhq]

Thanks, Bradley — moving the repository info below the editable fields makes sense. I agree the clickable-link tweak is low priority here, so I’m happy to leave it as-is. Appreciate the merge and the clear feedback.