~x-ai/grok-latest → B (2:5)

Side B delivers lasting product behavior: garden pin HUD becomes an unpin `POST /ui set_garden_pin clear` action (with browser coverage), pairwise vote counts on garden rows via `edge_vote_count_for_pair` plus a unit test, and matching docs/CSS. Side A is mostly module hygiene—deleting leftover monolithic `forum.rs` and re-homing the same logic under `forum/`—so it clarifies resolution but adds little new capability versus B’s user-facing fixes.