Add 5 procedural LED effects, gradient presets, auto-crop min aspect ratio, static source polling optimization

New features:
- Procedural effect source type with fire, meteor, plasma, noise, and aurora algorithms
  using palette LUT system and 1D value noise generator
- 12 predefined gradient presets (rainbow, sunset, ocean, forest, fire, lava, aurora,
  ice, warm, cool, neon, pastel) selectable from a dropdown in the gradient editor
- Auto-crop filter: min aspect ratio parameter to prevent false-positive cropping
  in dark scenes on ultrawide displays

Optimization:
- Static/gradient sources without animation: stream thread sleeps 0.25s instead of
  frame_time; processor repolls at frame_time instead of 5ms (~40x fewer iterations)
- Inverted isinstance checks in routes to test for PictureColorStripSource only

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

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

@@ -89,7 +89,8 @@ import {
 // Layer 5: color-strip sources
 import {
     showCSSEditor, closeCSSEditorModal, forceCSSEditorClose, saveCSSEditor, deleteColorStrip,
-    onCSSTypeChange, onAnimationTypeChange, colorCycleAddColor, colorCycleRemoveColor,
+    onCSSTypeChange, onEffectTypeChange, onAnimationTypeChange, colorCycleAddColor, colorCycleRemoveColor,
+    applyGradientPreset,
 } from './features/color-strips.js';
 
 // Layer 5: calibration
@@ -274,9 +275,11 @@ Object.assign(window, {
     saveCSSEditor,
     deleteColorStrip,
     onCSSTypeChange,
+    onEffectTypeChange,
     onAnimationTypeChange,
     colorCycleAddColor,
     colorCycleRemoveColor,
+    applyGradientPreset,
 
     // calibration
     showCalibration,