feat v1.31.0: room cards — metrics line + proportional resize

- room label becomes a card: name on top, optional metrics below
  (temperature / humidity / avg zigbee / lights), four checkboxes in
  space settings, all off by default; lights render On/Off or '1 of 3'
- areaHum + areaLightStats pure helpers (+3 unit tests, 90 total)
- resize via corner handles in the Plan editor (hover), uniform 0.5-3x,
  scale stored as layout k next to the position; drag preserves it
- fix latent v1.25 regression: draggable HTML labels were never rendered
  in the Plan editor (static SVG only) — real name-only cards now render
  there, draggable and resizable
- repair merge/split smokes still calling removed _toggleMarkup
- validation.py: 4 label_* bools; smoke_room_cards.mjs; docs same-commit

docs/TESTING.md

@@ -140,6 +140,13 @@ Run the *core flows* (marked ★ below) in each environment at least once per mi
       (explicit ripple color still wins); off/white lights unchanged [auto]
 - [ ] Alarm pulse (v1.27.0): leak/smoke/gas/CO/siren in 'on' pulse a red ring over any
       display mode; clears on 'off'; unavailable never alarms [auto]; reduced-motion static
+- [ ] Room cards (v1.31.0): with metrics enabled in space settings (4
+      checkboxes: temperature, humidity, avg Zigbee, lights) the room name gets
+      a smaller metrics line under it; lights show On/Off or "1 of 3" when
+      partially lit; rooms without an HA area show the name only; in the Plan
+      editor cards show the name only, are draggable and resizable via corner
+      handles on hover (uniform scale 0.5–3, stored in layout, survives drag);
+      View mode has no handles/hover [auto]
 - [ ] Esc closes dialogs (v1.30.4): Escape closes the topmost dialog (opening
       info, device info, icon rules, general settings, device editor, opening
       editor, space dialog incl. abandoning an import queue); stacked dialogs