Replace auto-start with startup automation, add card colors to dashboard

- Add `startup` automation condition type that activates on server boot,
  replacing the per-target `auto_start` flag
- Remove `auto_start` field from targets, scene snapshots, and all API layers
- Remove auto-start UI section and star buttons from dashboard and target cards
- Remove `color` field from scene presets (backend, API, modal, frontend)
- Add card color support to scene preset cards (color picker + border style)
- Show localStorage-backed card colors on all dashboard cards (targets,
  automations, sync clocks, scene presets)
- Fix card color picker updating wrong card when duplicate data attributes
  exist by using closest() from picker wrapper instead of global querySelector
- Add sync clocks step to Sources tab tutorial
- Bump SW cache v9 → v10

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

server/src/wled_controller/static/js/features/tutorials.js

@@ -56,7 +56,8 @@ const sourcesTourSteps = [
     { selector: '[data-stream-tab="static_image"]', textKey: 'tour.src.static', position: 'bottom' },
     { selector: '[data-stream-tab="processed"]', textKey: 'tour.src.processed', position: 'bottom' },
     { selector: '[data-stream-tab="audio"]', textKey: 'tour.src.audio', position: 'bottom' },
-    { selector: '[data-stream-tab="value"]', textKey: 'tour.src.value', position: 'bottom' }
+    { selector: '[data-stream-tab="value"]', textKey: 'tour.src.value', position: 'bottom' },
+    { selector: '[data-stream-tab="sync"]', textKey: 'tour.src.sync', position: 'bottom' }
 ];
 
 const automationsTutorialSteps = [