openai/gpt-chat-latest → B (4:1)

Side B adds substantive new infrastructure: typed form-template substitution (`$form:i32`) with tests, a `next` navigation flow after recording votes, new routing/hooks for a vote page, and supporting UI behavior (slider initialization and redirect handling). Side A mainly tightens an invariant by replacing `unwrap_or(0)` with `expect(...)`, updates documentation/tests to enforce 0-based thread indices, and always renders the post link; these are useful correctness and clarity improvements but are narrower in lasting impact.