msobczyk/handle signals in docker entrypoint

handle signals in docker entrypoint, handle exit in start_clive script (close container on terminal close), closes issue #274 (closed)

clive/__private/run_tui.py

@@ -5,6 +5,8 @@ import signal
 import sys
 import warnings
 
+from clive.__private.core.clive_import import get_clive
+
 
 def _hide_never_awaited_warnings_in_non_dev_mode() -> None:
     from clive.dev import is_in_dev_mode
@@ -14,9 +16,8 @@ def _hide_never_awaited_warnings_in_non_dev_mode() -> None:
 
 
 async def _shutdown_tui_gracefully() -> None:
-    from clive.__private.ui.app import Clive
-
-    await Clive.app_instance().action_quit()
+    app = get_clive().app_instance()
+    await app.action_quit()
     asyncio.get_event_loop().stop()