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_access_card.py

@@ -1,4 +1,4 @@
-from gpu_rent.access_card import collect_access_links, mcp_snippet_lines
+from gpu_rent.access_card import collect_access_links, mcp_snippet_lines, render_access_panel
 
 
 class _Cfg:
@@ -6,6 +6,7 @@ class _Cfg:
     llm_runtime = "ollama"
     ollama_local_port = 17811
     llamacpp_local_port = 17812
+    enable_swarmui = True
 
 
 def test_collect_links_swarm_and_ollama(monkeypatch):
@@ -29,3 +30,16 @@ def test_collect_links_no_tunnel():
 def test_mcp_snippet_json():
     lines = mcp_snippet_lines(_Cfg())
     assert any("17801/mcp" in line for line in lines)
+
+
+def test_access_panel_red_when_killer_failed(monkeypatch):
+    monkeypatch.setattr(
+        "gpu_rent.access_card.load_state",
+        lambda: type(
+            "S",
+            (),
+            {"notes": {"idle_killer": "failed", "idle_killer_error": "no cred"}},
+        )(),
+    )
+    panel = render_access_panel(_Cfg(), tunneled=True)
+    assert panel.border_style == "red"