Add pytest plugin for CI integration

[telsav]

Currently flutter-skill is used interactively through MCP. It would be great to have a pytest plugin that lets people run AI-driven tests in CI:

def test_login(flutter_skill):
    flutter_skill.prompt('Test the login flow with test@example.com')
    assert flutter_skill.find_element('Dashboard')

What's needed:

• A Python package pytest-flutter-skill
• Connects to flutter-skill MCP server
• Wraps MCP tools as Python assertions

Great for Python developers who want to contribute!