fix+ux v1.15.1: display-settings round from live usage

- comfort bounds: parseFloat+isFinite guard (empty input collapsed a bound to 0
  and the auto-swap made 'comfort from 25' behave as 0-25 → green at 24°)
- avg room temperature in the room tooltip (what the temp fill actually uses)
- hover darkens the current fill instead of recoloring blue; grey when unfilled
- fill mode as a radio group with short labels; compact inline bounds inputs
- space dialog widened to 500px; TESTING.md updated in the same commit

package.json

@@ -1,6 +1,6 @@
 {
   "name": "houseplan-card",
-  "version": "1.15.0",
+  "version": "1.15.1",
   "description": "Interactive house plan Lovelace card for Home Assistant",
   "license": "MIT",
   "type": "module",