Enhance SwarmUI integration and GPU environment verification

- Updated CLI documentation to reflect the new handling of `CIVITAI_API_TOKEN`, which is now automatically passed to SwarmUI user settings during startup.
- Improved the `render_access_panel` function to include additional warnings for idle-killer failures and stack errors, enhancing user feedback.
- Introduced a new function `seed_swarmui_api_keys` to manage API key injection into SwarmUI, ensuring seamless integration with the Model Downloader.
- Enhanced GPU environment verification logic to include fail-fast checks for critical components like CUDA, improving error handling and user notifications.
- Updated tests to validate the new API key handling and access panel behavior, ensuring robustness in the integration process.

tests/test_swarmui_api_keys.py

@@ -0,0 +1,52 @@
+"""Tests for remote swarmui_set_api_keys."""
+
+from __future__ import annotations
+
+import importlib.util
+import json
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+REMOTE = ROOT / "src" / "gpu_rent" / "remote" / "swarmui_set_api_keys.py"
+
+
+def _load():
+    spec = importlib.util.spec_from_file_location("swarmui_set_api_keys", REMOTE)
+    assert spec and spec.loader
+    mod = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+    return mod
+
+
+def test_set_civitai_key(tmp_path, monkeypatch):
+    mod = _load()
+    keys = tmp_path / "keys.json"
+    keys.write_text(json.dumps({"civitai_api": "tok-123"}), encoding="utf-8")
+    monkeypatch.setattr(mod, "KEYS_PATH", keys)
+
+    calls = []
+
+    def fake_post(path, payload, timeout=15.0):
+        calls.append((path, payload))
+        if path == "/API/GetNewSession":
+            return {"session_id": "sid-1"}
+        if path == "/API/SetAPIKey":
+            assert payload["session_id"] == "sid-1"
+            assert payload["keyType"] == "civitai_api"
+            assert payload["key"] == "tok-123"
+            return {"success": True}
+        raise AssertionError(path)
+
+    monkeypatch.setattr(mod, "post", fake_post)
+    monkeypatch.setattr(mod, "wait_session", lambda _d: "sid-1")
+    assert mod.main() == 0
+    assert not keys.exists()
+    assert any(c[0] == "/API/SetAPIKey" for c in calls)
+
+
+def test_skip_empty_keys(tmp_path, monkeypatch):
+    mod = _load()
+    keys = tmp_path / "keys.json"
+    keys.write_text("{}", encoding="utf-8")
+    monkeypatch.setattr(mod, "KEYS_PATH", keys)
+    assert mod.main() == 0