[Design]: Improve direct GDSFactory component S-parameter workflow

[QuentinWach]

Summary

Adds a BeamZ-owned, transparent GDSFactory workflow under beamz.design.gdsfactory.

• Prepares GDSFactory components as native BeamZ designs, ports, sources, and monitors.
• Adds local S-parameter orchestration with provenance and numerical checks.
• Adds direct GDSFactory documentation and a flagship component-to-S-parameters notebook.
• Adds v0.5.0 metadata plus tag-only wheel/sdist qualification, including a packaged local smoke run.

Validation

• Targeted GDSFactory and release-version tests passed.
• Documentation notebook contract tests passed.
• Docs built with strict MkDocs.
• Built v0.5.0 wheel and sdist successfully.
• Executed the new notebook and package smoke flow against the built wheel.

Notes

This PR does not create a release, tag, or publish to PyPI. The downstream gds_fdtd adapter migration remains a separate repository change.