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/CLAUDE.md

@@ -130,6 +130,31 @@ After restarting the server with new code:
 
 ## Frontend UI Patterns
 
+### Entity Cards
+
+All entity cards (devices, targets, CSS sources, streams, scenes, automations, etc.) **must support clone functionality**. Clone buttons use the `ICON_CLONE` (📋) icon in `.card-actions`.
+
+**Clone pattern**: Clone must open the entity's add/create modal with fields prefilled from the cloned item. It must **never** silently create a duplicate — the user should review and confirm.
+
+Implementation:
+
+1. Export a `cloneMyEntity(id)` function that fetches (or finds in cache) the entity data
+2. Call the add/create modal function, passing the entity data as `cloneData`
+3. In the modal opener, detect clone mode (no ID + cloneData present) and prefill all fields
+4. Append `' (Copy)'` to the name
+5. Set the modal title to the "add" variant (not "edit")
+6. The save action creates a new entity (POST), not an update (PUT)
+
+```javascript
+export async function cloneMyEntity(id) {
+    const entity = myCache.data.find(e => e.id === id);
+    if (!entity) return;
+    showMyEditor(null, entity);  // null id = create mode, entity = cloneData
+}
+```
+
+Register the clone function in `app.js` window exports so inline `onclick` handlers can call it.
+
 ### Modal Dialogs
 
 **IMPORTANT**: All modal dialogs must follow these standards for consistent UX: