Update documentation and CLI behavior for GPU management

- Clarified the behavior of `Ctrl+C` and `Ctrl+D` in the README and other documentation, specifying that `Ctrl+C` only stops the tunnel while keeping the GPU active, and `Ctrl+D` stops the GPU while preserving disk data.
- Enhanced the CLI documentation to reflect these changes, ensuring users understand the implications of these commands during GPU operations.
- Improved the handling of data bindings and remounting logic in the codebase to prevent issues with empty model tabs in the UI.
- Added tests to validate the new command behaviors and ensure proper documentation alignment.

tests/test_wait_backend_idle.py

@@ -138,9 +138,34 @@ def test_swarm_diag_script_covers_api_and_journal():
 
     text = files("gpu_rent.remote").joinpath("swarm_diag.py").read_text(encoding="utf-8")
     assert "ListBackends" in text
+    assert "ListModels" in text
     assert "journalctl" in text
     assert ".gpu-rent-last-diag.txt" in text
     assert "nvidia-smi" in text
+    assert "findmnt /opt/swarmui/Models" in text
+
+
+def test_ensure_binds_refuses_lazy_umount():
+    from importlib.resources import files
+
+    sh = files("gpu_rent.remote").joinpath("ensure_binds.sh").read_text(encoding="utf-8")
+    assert "umount -l" in sh  # mentioned as forbidden
+    assert 'umount -l "$dst"' not in sh
+    assert "mount --bind" in sh
+    assert "weights data=" in sh
+
+    comfy = files("gpu_rent.remote").joinpath("install_swarm_comfy.py").read_text(
+        encoding="utf-8"
+    )
+    assert '"umount", "-l"' not in comfy
+
+    from pathlib import Path
+
+    session = (Path(__file__).resolve().parents[1] / "src" / "gpu_rent" / "session.py").read_text(
+        encoding="utf-8"
+    )
+    assert "umount -l" not in session
+    assert "ensure_data_binds" in session
 
 
 def test_verify_gpu_env_fail_fast_empty_dlbackend(monkeypatch):