Enhance ExtraArgs sanitization and backend recovery logic

- Introduced the `clean_extra_args` function to filter out unsafe CLI flags and comment garbage from `ExtraArgs`, improving backend configuration integrity.
- Updated the `repair_extra_args_on_disk` function to rewrite corrupted `ExtraArgs` lines in the FDS file, ensuring cleaner backend settings.
- Enhanced the `recover_errored_backends` function to utilize the new sanitization logic, preserving valid `ExtraArgs` during backend reconfiguration.
- Improved the `sanitize_backends_fds` function to drop comment garbage and retain valid entries, enhancing overall backend management.
- Added tests to validate the new sanitization behavior, ensuring robustness in handling `ExtraArgs` during backend operations.

tests/test_tune_swarm_perf.py

@@ -189,6 +189,22 @@ def test_sanitize_does_not_eat_newline_on_bare_empty(tmp_path, monkeypatch):
     assert backends.read_text(encoding="utf-8") == original
 
 
+def test_sanitize_drops_comment_garbage_extra_args(tmp_path, monkeypatch):
+    mod = _load()
+    backends = tmp_path / "Backends.fds"
+    junk = (
+        '\tExtraArgs: "#If unchecked, the system will automatically add some '
+        'relevant arguments to the comfy launch."\n'
+        "\tStartScript: /mnt/x/main.py\n"
+    )
+    backends.write_text(junk, encoding="utf-8")
+    monkeypatch.setattr(mod, "BACKENDS", backends)
+    assert mod.sanitize_backends_fds() is True
+    text = backends.read_text(encoding="utf-8")
+    assert "unchecked" not in text
+    assert "StartScript: /mnt/x/main.py" in text
+
+
 def test_ensure_absolute_start_script(tmp_path, monkeypatch):
     mod = _load()
     data = tmp_path