fix(extensions): guard against non-dict command entries in _validate()

If provides.commands contains a non-mapping entry (e.g. an int or string),
'name' not in cmd raises TypeError instead of a user-facing ValidationError.
Added isinstance(cmd, dict) check at the top of the loop.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: iamaeroplane

src/specify_cli/extensions.py

@@ -219,6 +219,10 @@ def _validate(self):
         # Validate commands; track renames so hook references can be rewritten.
         rename_map: Dict[str, str] = {}
         for cmd in commands:
+            if not isinstance(cmd, dict):
+                raise ValidationError(
+                    "Each command entry in 'provides.commands' must be a mapping"
+                )
             if "name" not in cmd or "file" not in cmd:
                 raise ValidationError("Command missing 'name' or 'file'")