Add clone support for scene and automation cards, update sync clock descriptions

- Scene clone: opens capture modal with prefilled name/description/targets
  instead of server-side duplication; removed backend clone endpoint
- Automation clone: opens editor with prefilled conditions, scene, logic,
  deactivation mode (webhook tokens stripped for uniqueness)
- Updated sync clock i18n descriptions to reflect speed-only-on-clock model
- Added entity card clone pattern documentation to server/CLAUDE.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/locales/en.json

@@ -652,6 +652,7 @@
   "automations.created": "Automation created",
   "automations.deleted": "Automation deleted",
   "automations.error.name_required": "Name is required",
+  "automations.error.clone_failed": "Failed to clone automation",
   "scenes.title": "Scenes",
   "scenes.add": "Capture Scene",
   "scenes.edit": "Edit Scene",
@@ -1172,7 +1173,7 @@
   "sync_clock.name.placeholder": "Main Animation Clock",
   "sync_clock.name.hint": "A descriptive name for this synchronization clock",
   "sync_clock.speed": "Speed:",
-  "sync_clock.speed.hint": "Speed multiplier shared by all linked sources. 1.0 = normal speed.",
+  "sync_clock.speed.hint": "Animation speed multiplier for all linked sources. 1.0 = normal, 2.0 = double speed, 0.5 = half speed.",
   "sync_clock.description": "Description (optional):",
   "sync_clock.description.placeholder": "Optional description",
   "sync_clock.description.hint": "Optional notes about this clock's purpose",
@@ -1189,7 +1190,7 @@
   "sync_clock.paused": "Clock paused",
   "sync_clock.resumed": "Clock resumed",
   "sync_clock.reset_done": "Clock reset to zero",
-  "sync_clock.delete.confirm": "Delete this sync clock? Sources using it will revert to their own speed.",
+  "sync_clock.delete.confirm": "Delete this sync clock? Linked sources will lose synchronization and run at default speed.",
   "color_strip.clock": "Sync Clock:",
-  "color_strip.clock.hint": "Link to a sync clock for synchronized animation. When set, speed comes from the clock."
+  "color_strip.clock.hint": "Link to a sync clock to synchronize animation timing across sources. Speed is controlled on the clock."
 }