SpecPi 0.19.1

Fix delegation failing with “Delegation cannot inherit this parent runtime provider override” for GitHub Copilot models, including switching Luna → Anthropic Opus → Luna.

SpecPi now accepts Pi's exact public Copilot client-identification headers when the child independently reconstructs them. Runtime authentication overrides, extension-provider overrides, extra headers, and model mismatches remain blocked.

Update the harness and restart Pi:

npm install --global specpi@0.19.1
specpi update
specpi doctor

SpecPi Chat stays at 0.4.1; no Chat update is needed for this fix. In Chat, use Restart Pi after updating the harness.

Validated with the full repository suite, isolated package and installer lifecycle checks, real Pi child-session regressions, and desktop, tablet, and mobile site checks.

Changes: #46