openai/gpt-chat-latest → A (4:1)

Side A resolves a structural module issue by deleting the obsolete monolithic `server/src/html/forum.rs`, adding `forum/mod.rs`, and moving the implementation into focused submodules (`feed.rs`, `views.rs`, `page.rs`, `paginator.rs`, `post_single.rs`, `profile.rs`, `thread_morph.rs`), ensuring `mod forum` unambiguously resolves to `forum/mod.rs` and improving maintainability without changing behavior. Side B makes a smaller semantic cleanup by changing rank-history post indexes to the project's 0-based URL convention, replacing silent fallbacks with `expect(...)`, updating links, comments, and tests, but its impact is narrower.