[refactor] Docker Operations Abstraction

[san-ghun]

The Docker operations could be better abstracted into a dedicated class:

class DockerManager:
    def __init__(self, workspace: str):
        self.workspace = workspace
        
    def ensure_container_running(self) -> bool:
        """Ensure the tiny42 container is running."""
        pass
        
    def execute_command(self, command: str) -> None:
        """Execute a command in the container."""
        pass
        
    def rebuild_container(self) -> None:
        """Rebuild the container from scratch."""
        pass