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_session.py

@@ -51,6 +51,10 @@ def _mock_bind(monkeypatch):
         "gpu_rent.session.ensure_swarm_comfy_installed",
         lambda cfg, host, log: None,
     )
+    monkeypatch.setattr(
+        "gpu_rent.session.seed_autocomplete",
+        lambda cfg, host, log: False,
+    )
     monkeypatch.setattr("gpu_rent.session.wait_backend_idle", lambda cfg, host, log, **kw: None)
     monkeypatch.setattr(
         "gpu_rent.session.verify_stack_on_vm",
@@ -64,6 +68,10 @@ def _mock_bind(monkeypatch):
         "gpu_rent.session.tune_swarm_perf",
         lambda cfg, host, log: False,
     )
+    monkeypatch.setattr(
+        "gpu_rent.session.ensure_data_binds",
+        lambda cfg, host, log, **kw: None,
+    )
     monkeypatch.setattr(
         "gpu_rent.session.ensure_boot_snapshot",
         lambda conn, boot_volume_id, cfg, log: None,