Adapt to DeepSeek Harness 0.1.2-alpha.1

[flyingcoding]

Summary

• migrate browser credential reads and writes from the removed connection.api surface to ctx.remote.credentials, including credential invalidations
• replace the removed dsh-client-runtime dependency with the 0.1.2 dsh-client-store platform module and current UI renderer injection
• align tool-call IDs with the current branded stream vocabulary and remove the obsolete global sessions.selectModel monkey patch
• update peer metadata, tests, package metadata, and the changelog for DeepSeek Harness 0.1.2-alpha.1

Validation

• npm ci
• npm run typecheck
• npm test — 211 tests passed
• npm run build
• npm pack --dry-run
• typechecked directly against the installed DeepSeek Harness 0.1.2-alpha.1 package set
• installed the branch into a real dsh web 0.1.2-alpha.1 profile and verified the Command Code settings page, usage data, credential controls, and multi-account controls in the browser with no console warnings or errors

Packaging note

The 0.1.2 workspace packages are not all available from the public npm registry yet. Runtime peer ranges target 0.1.2-alpha.1, while dev dependencies remain on the published RC packages so npm ci stays reproducible. The small compile-time client-store declaration is erased from the bundle; the running 0.1.2 host supplies the actual platform module.