feat: new value source types (HA entity, gradient map, strip extract) + UI fixes

New value source types:
- ha_entity: reads numeric values from HA entity state/attribute, normalizes
  via min/max range, applies EMA smoothing. EntitySelect for HA connection
  and entity selection with live entity list fetching.
- gradient_map: maps a float value source (0-1) through a gradient entity.
  EntitySelect for both input source and gradient with inline previews.
- css_extract: extracts single color by averaging LED range from a color
  strip source. EntitySelect for source selection.

Value source type picker:
- Filter tabs (All / Numeric / Color) above the icon grid
- showTypePicker extended with filterTabs + onFilterChange support

Palette selectors converted to EntitySelect:
- Effect palette, gradient preset, and audio palette selectors now use
  command-palette style EntitySelect with gradient strip previews

Tab indicator fixes:
- Icon now updates on tab switch (was passing no args to updateTabIndicator)
- Visible with any background effect active, not just Noise Field
- Noise Field is the default background effect for new users

Dashboard section collapse fix:
- Split header into clickable toggle (chevron+label) and non-clickable
  actions area — buttons no longer trigger collapse/expand

Discriminated union fix (422 errors):
- source_type/target_type now always included in update payloads for:
  CSS editor, LED target, HA light target, simple calibration,
  advanced calibration

server/src/wled_controller/static/js/features/graph-editor.ts

@@ -682,7 +682,7 @@ async function _fetchAllEntities(): Promise<Record<string, any>> {
         devicesCache.fetch(), captureTemplatesCache.fetch(), ppTemplatesCache.fetch(),
         streamsCache.fetch(), audioSourcesCache.fetch(), audioTemplatesCache.fetch(),
         valueSourcesCache.fetch(), colorStripSourcesCache.fetch(), syncClocksCache.fetch(),
-        outputTargetsCache.fetch(), patternTemplatesCache.fetch(), scenePresetsCache.fetch(),
+        outputTargetsCache.fetch(), patternTemplatesCache.fetch().catch(() => []), scenePresetsCache.fetch(),
         automationsCacheObj.fetch(), csptCache.fetch(),
         fetchWithAuth('/output-targets/batch/states').catch(() => null),
     ]);