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/schemas/scene_presets.py

@@ -12,7 +12,6 @@ class TargetSnapshotSchema(BaseModel):
     color_strip_source_id: str = ""
     brightness_value_source_id: str = ""
     fps: int = 30
-    auto_start: bool = False
 
 
 class ScenePresetCreate(BaseModel):
@@ -20,7 +19,6 @@ class ScenePresetCreate(BaseModel):
 
     name: str = Field(description="Preset name", min_length=1, max_length=100)
     description: str = Field(default="", max_length=500)
-    color: str = Field(default="#4fc3f7", description="Card accent color")
     target_ids: Optional[List[str]] = Field(None, description="Target IDs to capture (all if omitted)")
 
 
@@ -29,7 +27,6 @@ class ScenePresetUpdate(BaseModel):
 
     name: Optional[str] = Field(None, min_length=1, max_length=100)
     description: Optional[str] = Field(None, max_length=500)
-    color: Optional[str] = None
     order: Optional[int] = None
 
 
@@ -39,7 +36,6 @@ class ScenePresetResponse(BaseModel):
     id: str
     name: str
     description: str
-    color: str
     targets: List[TargetSnapshotSchema]
     order: int
     created_at: datetime