Animation None option, FPS min 1, serial COM lifecycle fixes

- Replace animation Enable checkbox with None option in effect selector;
  show effect description tooltip; disable speed slider when None selected
- Allow target FPS range 1-90 (was 10-90) across UI and backend validation
- Scope serial COM connections to target lifetime (no idle caching);
  use temporary connections for power-off/test mode
- Fix serial black frame on stop: flush after write, delay after task
  cancel to prevent race with in-flight thread pool write

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

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

@@ -89,7 +89,7 @@ import {
 // Layer 5: color-strip sources
 import {
     showCSSEditor, closeCSSEditorModal, forceCSSEditorClose, saveCSSEditor, deleteColorStrip,
-    onCSSTypeChange, colorCycleAddColor, colorCycleRemoveColor,
+    onCSSTypeChange, onAnimationTypeChange, colorCycleAddColor, colorCycleRemoveColor,
 } from './features/color-strips.js';
 
 // Layer 5: calibration
@@ -274,6 +274,7 @@ Object.assign(window, {
     saveCSSEditor,
     deleteColorStrip,
     onCSSTypeChange,
+    onAnimationTypeChange,
     colorCycleAddColor,
     colorCycleRemoveColor,