refactor(infra): cull unused infrastructure and file cache helpers

src/external_editor.py

@@ -140,17 +140,6 @@ def get_default_launcher() -> ExternalEditorLauncher:
     return launcher
 
 
-def resolve_project_editor_override(project_path: Optional[str]) -> Optional[str]:
-    if not project_path:
-        return None
-    from src import models
-    try:
-        proj = models.load_project(project_path)
-        return proj.get("default_editor")
-    except Exception:
-        return None
-
-
 def create_temp_modified_file(content: str) -> str:
     """
     [C: src/gui_2.py:App._open_patch_in_external_editor, tests/test_external_editor.py:TestHelperFunctions.test_create_temp_modified_file]