~anthropic/claude-sonnet-latest → B (6:4)

Side B fixes a real correctness bug (RwLock guard held across a match arm, invitable to deadlock, in RoomCreate/RoomGrant handlers) plus flaky-test root causes (missing HTTP timeouts, pipe-buffer deadlock in test harness log capture), all concrete and lasting improvements to reliability. Side A is a large structural refactor that consolidates duplicate web_post.rs handlers into a single /ui dispatcher and unifies session resolution, which is a reasonable cleanup but mostly moves/renames existing logic without fixing any bug, and its size is largely churn (route removal, JSON templating changes) rather than a necessary fix.