feat v1.15.0: temperature room fill (blue/green/yellow) with editable comfort bounds

- fill_mode 'temp': below comfort → #4fc3f7, inside → #66d17a, above → #ffd45c;
  bounds default 20-25°C, editable in the space dialog (visible only for this
  mode), swapped bounds tolerated; rooms without a temperature reading unfilled
- areaTemp(): average of the area devices' temperatures
- tests: roomFillColor temp bands + bounds, spaceDisplayOf defaults, areaTemp,
  backend schema (fill_mode temp + temp_min/temp_max); smoke_temp_fill.mjs
- TESTING.md updated in the same commit (policy)

tests_backend/test_validation.py

@@ -116,3 +116,12 @@ def test_space_display_settings():
     bad_mode = dict(ok, settings={"fill_mode": "rainbow"})
     with _pytest.raises(Exception):
         v.SPACE_SCHEMA(bad_mode)
+
+
+def test_space_temp_bounds():
+    """Temperature comfort bounds validate as floats; temp fill mode accepted."""
+    ok = {
+        "id": "f1", "title": "F", "aspect": 1.0, "view_box": [0, 0, 1, 1], "rooms": [],
+        "settings": {"fill_mode": "temp", "temp_min": 19.5, "temp_max": "24"},
+    }
+    v.SPACE_SCHEMA(ok)