openai/gpt-chat-latest → A (3:1)

Side A substantially improves the developer workflow by replacing a release-build fixture with a persistent `cargo watch`-based server, adding preferred-port selection, reusing seeded `fixture-data/`, rebasing saved URLs, and extending health-check timeouts for reliable iteration. Side B is largely a structural refactor that moves forum code into new modules and inlines small helper functions without changing behavior, with the only notable functional addition being a macOS-specific `sample-fixture` profiling script.