ci: run recovery-safety unit tests in host contribution workflow

[smailzhu]

Proposal

Add the oomwoo_recovery_safety unit tests to the python job in
host-contribution-tests.yml. They run on pushes to main and on pull requests.

This is a proposal. It adds pytest to a job that currently runs only stdlib
unittest with no pip install. That relaxes the job's dependency-free
boundary. Your call whether the trade is worth it.

Why

• recovery-safety handles bounded recovery escalation and safety-event pauses.
• 13 unit tests exist and pass. Nothing in CI runs them today.
• A regression in this logic would not turn CI red.
• The core ladder is pure Python. The adapter tests stub rclpy via sys.modules.
• So the suite runs on a bare runner: no ROS 2 graph, no Gazebo, no hardware.

Scope

• Host-level unit coverage.
• Complements the package's colcon build/test/test-result path, which builds
  and tests in a ROS 2 environment.
• Does not replace it. A test against a real ROS graph is future work.

Change

Two steps added to the python job:

• install pytest
• run PYTHONPATH="$PWD" python3 -m pytest test -q in the package root (rclpy stubbed)

Verification

Ran the updated workflow on a fork. All steps passed, including the new
recovery-safety step. It reported 13 passed (~0.04s in that run).

Trade-off

• Pro: cheap regression coverage for recovery logic CI currently ignores.
• Con: adds pytest + one pip install to a stdlib-only job. Unit coverage
  only, not full ROS integration.

[makers-pet]

Thank you!