Prepare 0.1.0 release candidate packaging smoke

[QUSETIONS]

What changed

• Fix minicode-headless --help so it exits before runtime configuration is loaded.
• Add a regression test for the headless help path.
• Add a wheel/sdist build-and-install smoke script covering the three public CLI entry points.
• Run that package smoke in the cross-platform CI matrix.
• Update the README verification count to the current full-suite result.

Why

The installed minicode-headless --help command previously attempted to load a model configuration and failed before displaying help. The packaging check now validates both source distributions and installed console scripts in clean virtual environments.

Validation

• 1311 passed, 2 skipped from the local full test suite.
• 18 passed from headless and packaging-focused tests.
• Wheel and sdist package smoke passed locally for all three CLI entry points.
• compileall and git diff --check passed.