feat(models): ask whether to delete the model file from disk

- The delete button now opens a dialog; for local models it includes an "also
  delete the model file from disk" checkbox (checked by default), so a pool
  entry can be removed while keeping the .cmf for later.
- DELETE /admin/api/models/:id accepts ?delete_file=true|false (default true).
  The shared-file guard still applies: a file referenced by another model is
  never removed.
- cmf_file_for_model now treats any loopback base_url as local (managed servers
  can sit on any port, not just the legacy local_port).

Cargo.lock

@@ -285,7 +285,7 @@ checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
 
 [[package]]
 name = "cortiq-gateway"
-version = "0.2.16"
+version = "0.2.17"
 dependencies = [
  "anyhow",
  "arc-swap",