fix: Add Windows compatibility and JupyterKernelClient fallback

[Yash-Kavaiya]

Fixes #100

Summary of Fixes

This PR adds native cross-platform support for Windows and resolves a runtime AttributeError:

1. Windows Console Compatibility (colab_cli/console.py):

   • Wrapped termios and tty imports in a try/except ImportError block.
   • Added guards around termios, tty, fileno(), and signal.SIGWINCH calls to prevent ModuleNotFoundError: No module named 'termios' on Windows.

2. Google Drive Auth /dev/tty Fallback (colab_cli/commands/automation.py):

   • Added a fallback for open("/dev/tty") on non-POSIX systems to use sys.stdin.readline().

3. JupyterKernelClient Fallback (colab_cli/runtime.py):

   • Fixed AttributeError: module 'jupyter_kernel_client' has no attribute 'KernelClient' in ColabRuntime.kernel_client by updating the fallback class name to jupyter_kernel_client.JupyterKernelClient.

Testing Verification

Verified end-to-end on Windows 11 with PowerShell:

• Created sessions using colab new --gpu T4 -s demo-session
• Handled OAuth flow & Drive automation
• Executed Python code & GPU workloads (nvidia-smi on Tesla T4 runtime)