feat(tests): add smoke tests and CI automation

[eduardofraga]

Summary

Add comprehensive smoke tests and enable automatic CI on push/PR.

Changes

• tests/smoke_build.sh — Docker image builds successfully
• tests/smoke_ansible.sh — ansible --version, ansible-playbook --version, ansible-inventory --help
• tests/smoke_python.sh — winrm and ansible Python imports verified
• tests/smoke_shell.sh — eval $1 passthrough and exit code propagation tested
• tests/smoke_playbook.sh — syntax check + local ping via tests/test.yml
• tests/test.yml — minimal Ansible playbook for smoke testing
• .github/workflows/test.yaml — runs on push/PR/manual; executes all smoke steps
• AGENTS.md — updated with accurate Docker-based test commands

Verification

All 5 smoke tests pass locally:

PASS: smoke_build
PASS: smoke_ansible
PASS: smoke_python
PASS: smoke_shell
PASS: smoke_playbook