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/api/routes/scene_presets.py

@@ -37,14 +37,12 @@ def _preset_to_response(preset: ScenePreset) -> ScenePresetResponse:
         id=preset.id,
         name=preset.name,
         description=preset.description,
-        color=preset.color,
         targets=[{
             "target_id": t.target_id,
             "running": t.running,
             "color_strip_source_id": t.color_strip_source_id,
             "brightness_value_source_id": t.brightness_value_source_id,
             "fps": t.fps,
-            "auto_start": t.auto_start,
         } for t in preset.targets],
         order=preset.order,
         created_at=preset.created_at,
@@ -76,7 +74,6 @@ async def create_scene_preset(
         id=f"scene_{uuid.uuid4().hex[:8]}",
         name=data.name,
         description=data.description,
-        color=data.color,
         targets=targets,
         order=store.count(),
         created_at=now,
@@ -143,7 +140,6 @@ async def update_scene_preset(
             preset_id,
             name=data.name,
             description=data.description,
-            color=data.color,
             order=data.order,
         )
     except ValueError as e: