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.

src/gpu_rent/doctor.py

@@ -422,7 +422,8 @@ def dry_run_plan(checks: list[Check]) -> list[str]:
         f"idle-killer: {cfg.idle_minutes} мин пустой очереди, льгота {cfg.idle_grace_minutes} мин",
         "₽: в API нет — смотри панель; диск 24/7 даже после stop",
         f"туннель: localhost:{cfg.swarmui_local_port} -> VM :7801",
-        "gpu-rent up --yes создаст GPU + SwarmUI и откроет туннель :17801 (Ctrl+C не гасит GPU)",
+        "gpu-rent up --yes создаст GPU + SwarmUI и откроет туннель :17801 "
+        "(Ctrl+C не гасит GPU, Ctrl+D гасит)",
         "только облако без туннеля: gpu-rent up --yes --no-tunnel",
     ]
     flavor = next((c.detail for c in checks if c.name == "flavor" and c.ok), None)