Add color_cycle as standalone source type; UI polish

- color_cycle is now a top-level source type (alongside picture/static/gradient)
  with a configurable color list and cycle_speed; defaults to full rainbow spectrum
- ColorCycleColorStripSource + ColorCycleColorStripStream: smooth 30 fps interpolation
  between user-defined colors, one full cycle every 20s at speed=1.0
- Removed color_cycle animation sub-type from StaticColorStripStream
- Color cycle editor: compact horizontal swatch layout, proper module-scope fix
  (colorCycleAdd/Remove now exposed on window, DOM-synced before mutations)
- Animation enabled + Frame interpolation checkboxes use toggle-switch style
- Removed Potential FPS metric from targets and KC targets metric grids

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/js/app.js

@@ -90,7 +90,7 @@ import {
 // Layer 5: color-strip sources
 import {
     showCSSEditor, closeCSSEditorModal, forceCSSEditorClose, saveCSSEditor, deleteColorStrip,
-    onCSSTypeChange,
+    onCSSTypeChange, colorCycleAddColor, colorCycleRemoveColor,
 } from './features/color-strips.js';
 
 // Layer 5: calibration
@@ -276,6 +276,8 @@ Object.assign(window, {
     saveCSSEditor,
     deleteColorStrip,
     onCSSTypeChange,
+    colorCycleAddColor,
+    colorCycleRemoveColor,
 
     // calibration
     showCalibration,