test: gracefully skip test_ai_tui_agent_harness on Windows

- Explicitly import skip `pty` and `termios` at the top level of `src/tests/test_ai_tui_agent_harness.py`.
- Windows runner does not support these native POSIX modules.

Co-authored-by: PR0M3TH3AN <[email protected]>

src/tests/test_ai_tui_agent_harness.py

@@ -6,6 +6,9 @@ import sys
 
 import pytest
 
+pytest.importorskip("pty")
+pytest.importorskip("termios")
+
 
 def _load_harness_module():
     repo_root = Path(__file__).resolve().parents[2]