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/storage/scene_preset.py

@@ -14,7 +14,6 @@ class TargetSnapshot:
     color_strip_source_id: str = ""
     brightness_value_source_id: str = ""
     fps: int = 30
-    auto_start: bool = False
 
     def to_dict(self) -> dict:
         return {
@@ -23,7 +22,6 @@ class TargetSnapshot:
             "color_strip_source_id": self.color_strip_source_id,
             "brightness_value_source_id": self.brightness_value_source_id,
             "fps": self.fps,
-            "auto_start": self.auto_start,
         }
 
     @classmethod
@@ -34,7 +32,6 @@ class TargetSnapshot:
             color_strip_source_id=data.get("color_strip_source_id", ""),
             brightness_value_source_id=data.get("brightness_value_source_id", ""),
             fps=data.get("fps", 30),
-            auto_start=data.get("auto_start", False),
         )
 
 
@@ -45,7 +42,6 @@ class ScenePreset:
     id: str
     name: str
     description: str = ""
-    color: str = "#4fc3f7"  # accent color for the card
     targets: List[TargetSnapshot] = field(default_factory=list)
     order: int = 0
     created_at: datetime = field(default_factory=datetime.utcnow)
@@ -56,7 +52,6 @@ class ScenePreset:
             "id": self.id,
             "name": self.name,
             "description": self.description,
-            "color": self.color,
             "targets": [t.to_dict() for t in self.targets],
             "order": self.order,
             "created_at": self.created_at.isoformat(),
@@ -69,7 +64,6 @@ class ScenePreset:
             id=data["id"],
             name=data["name"],
             description=data.get("description", ""),
-            color=data.get("color", "#4fc3f7"),
             targets=[TargetSnapshot.from_dict(t) for t in data.get("targets", [])],
             order=data.get("order", 0),
             created_at=datetime.fromisoformat(data.get("created_at", datetime.utcnow().isoformat())),