BEC-853: Add pytest config to ghostshell

[beca-oc]

Task

Fix failing tests in ghostshell. Currently 53 failing, 11 passing.

Current State

• pytest -v: 53 FAILED, 11 passed
• Most failures in test_integration.py and test_retry.py
• conftest.py and pytest config already exist

Acceptance Criteria

• pytest -v passes with 0 failures
• No tests deleted (fix them, don't remove them)
• No changes to production code unless tests reveal a real bug
• Committed on agent/BEC-853 branch

Linear

Tracks BEC-853

[beca-oc]

Fixed in PR #12. All 64 tests now pass.

Root cause: pytest-asyncio was not installed in the local environment. The 53 failing tests were all async functions that require pytest-asyncio (configured as asyncio_mode = "auto" in pyproject.toml). Fixed by installing dev dependencies via uv pip install -e ".[dev]".

Result: 64/64 tests passing (was 11/64).