~anthropic/claude-sonnet-latest → A (8:2)

Side A adds a genuinely useful diagnostic script (sample-fixture) and cleanly refactors the monolithic forum.rs into cohesive submodules (access, ingest, nav, new_thread, room_members), improving maintainability with minimal behavioral risk. Side B merely deletes an entire feature (the tree view UI, its routes, and its well-covered test suite) with no replacement or migration path, which removes functionality and prior test coverage rather than adding lasting value.