fix: preserve native provider auth

[unrelentingfox]

Summary

• preserve native provider authentication and metadata when wrapping streams
• use the one-argument native-provider registration overload
• add a Pi 0.86.1 regression test for authentication resolution
• update Pi development dependencies to 0.86.1

Problem

Hi! Very cool project, and exactly what I was looking for to avoid sharing personal info with inference providers!

However all of my model providers seemed to break after installing your extension. It turns out Pi 0.86.1 removes an existing native provider when the legacy registerProvider(providerId, config) overload is used. The masking stream wrapper then replaces the provider with a partial registration that has no authentication resolver. Model use fails with No API key found even when the provider was configured correctly.

Validation

• npm test — 216 tests passed
• npm run check
• npm run pack:dry
• git diff --check
• verified in a fresh Pi 0.86.1 process with a native authenticated provider

[Sevten]

Thanks for the contribution!