**Acceptance criteria:** - [ ] "Edit Vertices" activates Geoman edit mode; as vertices are dragged the buffer is recalculated and re-rendered in real time - [ ] Cancelling restores the original line and buffer - [ ] `PUT /api/entities/:id` on save; map updates with the new line and buffer - [ ] Delete removes the line from the map
Acceptance criteria:
PUT /api/entities/:idon save; map updates with the new line and buffer