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/locales/en.json

@@ -262,6 +262,7 @@
   "tour.src.processed": "Processed — apply post-processing effects like blur, brightness, or color correction.",
   "tour.src.audio": "Audio — analyze microphone or system audio for reactive LED effects.",
   "tour.src.value": "Value — numeric data sources used as conditions in automations.",
+  "tour.src.sync": "Sync Clocks — shared timers that synchronize animations across multiple sources.",
   "tour.auto.list": "Automations — automate scene activation based on time, audio, or value conditions.",
   "tour.auto.add": "Click + to create a new automation with conditions and a scene to activate.",
   "tour.auto.card": "Each card shows automation status, conditions, and quick controls to edit or toggle.",
@@ -584,7 +585,9 @@
   "automations.conditions.add": "Add Condition",
   "automations.conditions.empty": "No conditions — automation is always active when enabled",
   "automations.condition.always": "Always",
-  "automations.condition.always.hint": "Automation activates immediately when enabled and stays active. Use this to auto-start scenes on server startup.",
+  "automations.condition.always.hint": "Automation activates immediately when enabled and stays active.",
+  "automations.condition.startup": "Startup",
+  "automations.condition.startup.hint": "Activates when the server starts and stays active while enabled.",
   "automations.condition.application": "Application",
   "automations.condition.application.apps": "Applications:",
   "automations.condition.application.apps.hint": "Process names, one per line (e.g. firefox.exe)",
@@ -657,8 +660,6 @@
   "scenes.name.placeholder": "My Scene",
   "scenes.description": "Description:",
   "scenes.description.hint": "Optional description of what this scene does",
-  "scenes.color": "Card Color:",
-  "scenes.color.hint": "Accent color for the scene card on the dashboard",
   "scenes.targets": "Targets:",
   "scenes.targets.hint": "Select which targets to include in this scene snapshot",
   "scenes.capture": "Capture",
@@ -680,10 +681,6 @@
   "scenes.error.activate_failed": "Failed to activate scene",
   "scenes.error.recapture_failed": "Failed to recapture scene",
   "scenes.error.delete_failed": "Failed to delete scene",
-  "autostart.title": "Auto-start Targets",
-  "autostart.toggle.enabled": "Auto-start enabled",
-  "autostart.toggle.disabled": "Auto-start disabled",
-  "autostart.goto_target": "Go to target",
   "time.hours_minutes": "{h}h {m}m",
   "time.minutes_seconds": "{m}m {s}s",
   "time.seconds": "{s}s",
@@ -1110,13 +1107,11 @@
   "dashboard.error.automation_toggle_failed": "Failed to toggle automation",
   "dashboard.error.start_failed": "Failed to start processing",
   "dashboard.error.stop_failed": "Failed to stop processing",
-  "dashboard.error.autostart_toggle_failed": "Failed to toggle auto-start",
   "dashboard.error.stop_all": "Failed to stop all targets",
   "target.error.editor_open_failed": "Failed to open target editor",
   "target.error.start_failed": "Failed to start target",
   "target.error.stop_failed": "Failed to stop target",
   "target.error.clone_failed": "Failed to clone target",
-  "target.error.autostart_toggle_failed": "Failed to toggle auto-start",
   "target.error.delete_failed": "Failed to delete target",
   "targets.stop_all.none_running": "No targets are currently running",
   "targets.stop_all.stopped": "Stopped {count} target(s)",