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

custom_components/houseplan/manifest.json

@@ -16,5 +16,5 @@
   "issue_tracker": "https://github.com/Matysh/houseplan-card/issues",
   "requirements": [],
   "single_config_entry": true,
-  "version": "1.15.0"
+  "version": "1.15.1"
 }