marker: fine-grained filter ops, clean pcap on remove

Deleting or updating a marker no longer triggers a full NIO reapply
(reset_packet_filters + re-add), which closed/reopened every sibling
marker's pcap via uBridge. Instead operate on single filters:

- stop_marker: bridge delete_packet_filter + unlink the pcap (works with
  the node stopped; filter removal is skipped, the file is still deleted).
- update_marker: bpf/tag/direction → rebuild just that filter (delete + add);
  enabled → instant toggle; color/highlight_duration → stored only.
- compute delete_marker_capture / rebuild_marker_filter + per-node routes
  (DELETE /markers/{name}, PUT /markers/{name}/rebuild) + MarkerRebuild schema.

IOU overrides _ubridge_delete_marker_filter for iol_bridge; rebuild reuses
the already-overridden add/delete/set, so IOU needs no rebuild override.

gns3server/api/routes/compute/dynamips_nodes.py

@@ -409,3 +409,42 @@ async def pause_dynamips_markers(node: Router = Depends(dep_node)) -> None:
 async def resume_dynamips_markers(node: Router = Depends(dep_node)) -> None:
 
     await node._ubridge_marker_resume()
+
+
+@router.delete(
+    "/{node_id}/markers/{marker_name}",
+    status_code=status.HTTP_204_NO_CONTENT,
+    dependencies=[Depends(compute_authentication)]
+)
+async def delete_dynamips_marker_capture(
+    marker_name: str,
+    link_id: str = "",
+    node: Router = Depends(dep_node)
+) -> None:
+    """
+    Delete a marker's capture pcap (called by the controller when the marker is
+    removed) so the file is cleaned up even with the node stopped.
+    """
+
+    await node.delete_marker_capture(marker_name, link_id)
+
+
+@router.put(
+    "/{node_id}/markers/{marker_name}/rebuild",
+    dependencies=[Depends(compute_authentication)]
+)
+async def rebuild_dynamips_marker(
+    marker_name: str,
+    rebuild_data: schemas.MarkerRebuild,
+    node: Router = Depends(dep_node)
+) -> dict:
+    """
+    Re-install a single marker filter with new BPF/tag/direction (delete + add,
+    no bridge reset) so sibling markers' pcaps stay open.
+    """
+
+    await node.rebuild_marker_filter(
+        marker_name, rebuild_data.link_id, rebuild_data.bpf,
+        rebuild_data.tag, rebuild_data.direction, rebuild_data.enabled,
+    )
+    return {"marker_name": marker_name}