feat v1.24.0: general settings (global fill palette) + per-space LQI toggle

- General settings dialog: fill colors grouped by mode (light on/off, temp
  cold/ok/hot, lqi weak/strong), each with its own opacity; lqi fill lerps
  between the endpoints; stored in settings.fill_colors (defaults omitted);
  space-card uses the same palette
- per-space show_lqi toggle (badges + room tooltip line), inherits the card's
  show_signal when unset
- fillColorsOf/lerpColor/roomFillStyle helpers (+4 tests), backend schemas,
  smoke_general_settings; TESTING.md updated in the same commit

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "houseplan-card",
-  "version": "1.23.1",
+  "version": "1.23.2",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "houseplan-card",
-      "version": "1.23.1",
+      "version": "1.23.2",
       "license": "MIT",
       "dependencies": {
         "lit": "^3.1.3",