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/automations.py

@@ -24,6 +24,7 @@ from wled_controller.storage.automation import (
     Condition,
     DisplayStateCondition,
     MQTTCondition,
+    StartupCondition,
     SystemIdleCondition,
     TimeOfDayCondition,
     WebhookCondition,
@@ -70,6 +71,8 @@ def _condition_from_schema(s: ConditionSchema) -> Condition:
         return WebhookCondition(
             token=s.token or secrets.token_hex(16),
         )
+    if s.condition_type == "startup":
+        return StartupCondition()
     raise ValueError(f"Unknown condition type: {s.condition_type}")