Refactor backend status handling and improve idle management

- Updated the idle-killer logic to treat SwarmUI `empty` and `disabled` states as busy, preventing unnecessary idle time during provisioning.
- Enhanced the `wait_backend_idle` function to recognize suspended backends as ready, improving resource utilization and user feedback.
- Refined the `install_swarm_comfy` script to skip installation when backends are already present, streamlining the setup process.
- Improved the `resolve_llm_runtime` function to prioritize live configuration over stale state notes, ensuring accurate runtime detection.
- Added tests to validate the new backend status handling and idle management logic, ensuring robustness and reliability.

tests/test_hold_killer.py

@@ -147,6 +147,42 @@ def test_classify_loading_is_busy(monkeypatch):
     assert "loading" in detail
 
 
+def test_classify_empty_is_busy(monkeypatch):
+    """No backends yet (first Comfy install) must not start idle clock."""
+    mod = _load_remote()
+
+    class FakeResp:
+        def __init__(self, payload):
+            self._payload = payload
+
+        def read(self):
+            import json
+
+            return json.dumps(self._payload).encode()
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *args):
+            return False
+
+    def fake_urlopen(req, timeout=0, context=None):
+        url = getattr(req, "full_url", None) or req.get_full_url()
+        if "GetNewSession" in url:
+            return FakeResp({"session_id": "abc"})
+        return FakeResp(
+            {
+                "status": {"waiting_gens": 0, "live_gens": 0, "loading_models": 0},
+                "backend_status": {"status": "empty"},
+            }
+        )
+
+    monkeypatch.setattr(mod.urllib.request, "urlopen", fake_urlopen)
+    busy, detail = mod.swarm_busy("http://127.0.0.1:7801")
+    assert busy is True
+    assert "empty" in detail
+
+
 def test_classify_busy_queue(monkeypatch):
     mod = _load_remote()