openai/gpt-chat-latest → A (4:1)

Side A resolves the module layout by deleting the obsolete monolithic `server/src/html/forum.rs`, adding `forum/mod.rs`, and wiring the split implementation (`feed.rs`, `views.rs`, `thread_morph.rs`, `page.rs`, etc.) as the single module root, eliminating ambiguous `mod forum` resolution and making the refactoring canonical. Side B is a useful but narrowly scoped bug fix that defines `GITHUB_API_BASE_URL` to avoid a `NameError` when the OAuth callback needs a missing API base URL.