Add distribution board copy and delete controls

docs/circuit-list-editor-api.md

@@ -233,6 +233,21 @@ returns HTTP `409` with `PROJECT_HISTORY_OPERATION_UNAVAILABLE`.
     `{ "floorId": null, "supplyType": "AV", "expectedRevision": 13 }`
   - executes `distribution-board.update`; floor and supply type are restored
     together by persistent Undo/Redo
+- `POST /projects/:projectId/distribution-boards/:distributionBoardId/copy`
+  - body: `{ "name": "UV-02 Kopie", "expectedRevision": 14 }`
+  - duplicates the complete distribution-board subtree with new owning UUIDs
+    while preserving project-device and room links
+  - response includes the new `distributionBoard`, its `circuitList`, the
+    revision and current history state
+- `DELETE /projects/:projectId/distribution-boards/:distributionBoardId`
+  - body: `{ "expectedRevision": 15 }`
+  - removes the complete, exactly captured distribution-board subtree in one
+    transaction
+  - response includes `distributionBoardId`, the revision and current history
+    state
+- Copy and deletion use `distribution-board.insert-subtree` and
+  `distribution-board.delete-subtree`. Persistent Undo/Redo restores or
+  removes the same complete subtree, including protection devices.
 
 ### Project Floors and Rooms