Add generated module front-door handlers

[rickardvh]

Summary

• add schema-backed module_front_door runtime handler generation
• add schema-backed argparse_function_call runtime handler generation for argparse namespace mapping, target/profile setup, and optional payload emission
• avoid re-exporting declarative generated runtime-handler semantic functions through local runtime facades
• cover both handler types in public API tests

Proof

• uv run pytest -q
• uv run ruff check .
• uv run ty check

Downstream

Used by rickardvh/agentic-workspace#1654 to move module front doors and simple workspace command wrappers out of hand-owned adapters.