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/css/modal.css

@@ -599,3 +599,39 @@
 .gradient-stop-spacer {
     flex: 1;
 }
+
+/* ── Color Cycle editor ──────────────────────────────────────── */
+
+#color-cycle-colors-list {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 6px;
+    margin-bottom: 8px;
+}
+
+.color-cycle-item {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    gap: 2px;
+}
+
+.color-cycle-item input[type="color"] {
+    width: 36px;
+    height: 28px;
+    border: 1px solid var(--border-color);
+    border-radius: 4px;
+    padding: 1px;
+    cursor: pointer;
+    background: transparent;
+    flex-shrink: 0;
+}
+
+.color-cycle-remove-btn {
+    font-size: 0.6rem;
+    padding: 0;
+    width: 36px;
+    height: 14px;
+    min-width: unset;
+    line-height: 1;
+}