Add auto-start targets feature with dashboard section

- Add auto_start boolean field to PictureTarget model (persisted per-target)
- Wire auto_start through API schemas, routes, and store
- Auto-start targets on server boot in main.py lifespan
- Add star toggle button on target cards (next to delete button)
- Add auto-start section on dashboard between performance and profiles
- Remove auto-start section from profiles tab

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

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

@@ -88,7 +88,7 @@ import {
     showTargetEditor, closeTargetEditorModal, forceCloseTargetEditorModal, saveTargetEditor,
     startTargetProcessing, stopTargetProcessing,
     startTargetOverlay, stopTargetOverlay, deleteTarget,
-    cloneTarget, toggleLedPreview,
+    cloneTarget, toggleLedPreview, toggleTargetAutoStart,
     expandAllTargetSections, collapseAllTargetSections,
 } from './features/targets.js';
 
@@ -302,6 +302,7 @@ Object.assign(window, {
     deleteTarget,
     cloneTarget,
     toggleLedPreview,
+    toggleTargetAutoStart,
 
     // color-strip sources
     showCSSEditor,