feat: make OpenAdapt the canonical openadapt-flow launcher

[abrichr]

What changed

• makes openadapt-flow part of the base openadapt installation
• requires the governed hosted engine contract with openadapt-flow>=1.7.0,<2.0.0
• exposes current engine commands through the unified openadapt flow ... surface
• preserves lazy compatibility exports for optional capture, ML, eval, grounding, and retrieval packages
• updates package metadata, documentation, CI, contribution guidance, and import/CLI tests around the canonical launcher role

Why

The stable starred repository and package should route users directly to the current compiler/runtime instead of presenting historical model-training topology. The bounded minimum prevents a clean install from resolving Flow 1.6.0, which predates the sanitized-artifact and hosted-validation commands exposed by this launcher.

Impact

pip install openadapt provides the supported demonstration compiler and governed replay commands without requiring users to discover a sibling repository first. The registry lock resolves the released openadapt-flow==1.7.0 artifact; supported future updates remain within Flow 1.x.

Validation

• 20 tests passed, 1 skipped locally
• Ruff passed
• wheel metadata contains openadapt-flow<2.0.0,>=1.7.0
• installed registry artifact reports Flow 1.7.0 and exposes sanitize and validate-hosted