feat(ha-light): broadcast a single Color Value Source to all entities

HALightOutputTarget gains a `source_kind` field with two modes:
- `css` (existing): per-mapping LED segments averaged from a ColorStripSource.
- `color_vs` (new): one colour from a colour-returning ValueSource pushed to
  every mapped entity (mapping LED ranges are ignored in this mode).

Backend wiring:
- Schema/route: add `source_kind` + `color_value_source_id` to create/update/
  response payloads, with VS existence + return_type=color validation.
- Storage: persist new fields, with defensive `or ""` coalesce so legacy rows
  written via resolve_ref with None survive the str-typed response schema.
- Processor: ha_light_target_processor reworked to drive both source kinds
  (incl. update_target_settings hot-swap of source mode). New unit tests in
  tests/core/test_ha_light_target_processor.py and extended store tests.

Frontend:
- ha-light editor modal: collapsed Color Strip + Color VS into one
  "Color Source" picker with grouped headers; mappings list shows a
  mode-aware hint when broadcasting a single colour.
- EntityPalette: support non-selectable header rows (with keyboard / filter
  handling) for grouped source pickers.

Bundled UI polish (icon inheritance + cleanup):
- Custom card icons now flow into more surfaces: command palette, dashboard
  target cards, scene-preset target picker, calibration test-device picker,
  and the LED-target device picker. LED targets inherit their device's icon
  when none is set on the target itself.
- Empty mod-card icon plates render as a dashed "+" placeholder when an
  icon-picker hook is wired, so the action stays discoverable.
- Icon picker: distinct "HA light target" eyebrow label and supports
  HA-light cards (data-ha-target-id) for channel-colour resolution.
- Update banner: "View release" now opens the in-app Update settings tab
  instead of an external link; uses the sparkles icon.
- Color-strip delete: cleaner toast on 409 conflict.

server/tests/storage/test_output_target_store.py

@@ -2,6 +2,7 @@
 
 import pytest
 
+from ledgrab.storage.ha_light_output_target import HALightMapping, HALightOutputTarget
 from ledgrab.storage.output_target import OutputTarget
 from ledgrab.storage.output_target_store import OutputTargetStore
 from ledgrab.storage.wled_output_target import WledOutputTarget
@@ -188,3 +189,98 @@ class TestOutputTargetPersistence:
         assert isinstance(loaded, WledOutputTarget)
         assert loaded.tags == ["tv"]
         db.close()
+
+
+# ---------------------------------------------------------------------------
+# HA-light dual-mode source: CSS and color value source
+# ---------------------------------------------------------------------------
+
+
+class TestHALightSourceModes:
+    def test_legacy_payload_defaults_to_css_kind(self):
+        """Records persisted before source_kind existed must load as CSS mode."""
+        data = {
+            "id": "pt_legacy",
+            "name": "Legacy HA light",
+            "target_type": "ha_light",
+            "ha_source_id": "ha_1",
+            "color_strip_source_id": "css_1",
+            "light_mappings": [],
+            "created_at": "2025-01-01T00:00:00+00:00",
+            "updated_at": "2025-01-01T00:00:00+00:00",
+        }
+        target = OutputTarget.from_dict(data)
+        assert isinstance(target, HALightOutputTarget)
+        assert target.source_kind == "css"
+        assert target.color_strip_source_id == "css_1"
+        assert target.color_value_source_id == ""
+
+    def test_invalid_source_kind_falls_back_to_css(self):
+        data = {
+            "id": "pt_bad_kind",
+            "name": "Bad kind",
+            "target_type": "ha_light",
+            "ha_source_id": "ha_1",
+            "source_kind": "garbage",
+            "color_strip_source_id": "css_1",
+            "created_at": "2025-01-01T00:00:00+00:00",
+            "updated_at": "2025-01-01T00:00:00+00:00",
+        }
+        target = OutputTarget.from_dict(data)
+        assert target.source_kind == "css"
+
+    def test_create_ha_light_color_vs(self, store):
+        target = store.create_target(
+            "Mood lamp",
+            "ha_light",
+            ha_source_id="ha_1",
+            source_kind="color_vs",
+            color_value_source_id="vs_static_red",
+            ha_light_mappings=[HALightMapping(entity_id="light.lamp")],
+        )
+        assert isinstance(target, HALightOutputTarget)
+        assert target.source_kind == "color_vs"
+        assert target.color_value_source_id == "vs_static_red"
+        # Round-trip via dict
+        assert target.to_dict()["source_kind"] == "color_vs"
+
+    def test_round_trip_color_vs_persists(self, tmp_path):
+        from ledgrab.storage.database import Database
+
+        db_path = str(tmp_path / "ha_color_vs.db")
+        db = Database(db_path)
+        s1 = OutputTargetStore(db)
+        t = s1.create_target(
+            "Sunrise",
+            "ha_light",
+            ha_source_id="ha_1",
+            source_kind="color_vs",
+            color_value_source_id="vs_anim_1",
+            ha_light_mappings=[HALightMapping(entity_id="light.bed")],
+        )
+        s2 = OutputTargetStore(db)
+        loaded = s2.get_target(t.id)
+        assert isinstance(loaded, HALightOutputTarget)
+        assert loaded.source_kind == "color_vs"
+        assert loaded.color_value_source_id == "vs_anim_1"
+        db.close()
+
+    def test_update_switches_source_kind(self, store):
+        target = store.create_target(
+            "Switcher",
+            "ha_light",
+            ha_source_id="ha_1",
+            color_strip_source_id="css_1",
+            ha_light_mappings=[HALightMapping(entity_id="light.x")],
+        )
+        assert target.source_kind == "css"
+        updated = store.update_target(
+            target.id,
+            source_kind="color_vs",
+            color_value_source_id="vs_color_1",
+        )
+        assert isinstance(updated, HALightOutputTarget)
+        assert updated.source_kind == "color_vs"
+        assert updated.color_value_source_id == "vs_color_1"
+        # CSS id is preserved (non-destructive switch)
+        assert updated.color_strip_source_id == "css_1"