Owner 2026-08-04: «углы границ комнат всё ещё с зубцами (фиксили для
декоративных линий, они теперь заканчиваются полукружьями, надо сделать
так же для границ комнат)».
A default miter join on a sharp room corner shoots a spike far past the
two walls that meet there, and flips to a flat bevel once the miter
limit clips it — both read as a tooth. Room borders now join ROUND:
* .room (polygon / evenodd path / rect) — one rule, so the plan view,
the Plan editor and the static space-card all get it;
* .room-outline — a room with open boundaries draws its walls as
separate M..L subpaths, so its corners are stroke ENDS: round caps
close them the same way a round join closes a contour;
* .seg — the contour being drawn in the editor already had round caps,
now it states the join too.
smoke_render_parity checks both renderers and the trimmed outline;
demo/shot_room_joins.mjs is the before/after still (a 45° apex).
