v0.3.1

Summary

• Bump Agent Browser Core workspace and package release metadata to 0.3.1.
• Update internal Browser package dependency pins and release compatibility metadata.
• Update CI/release tests and publish dry-run expectations for v0.3.1.

Verification

• npm run verify
• npm run verify:packages
• npm run verify:release-version -- v0.3.1
• npm run publish:packages:dry-run
• git diff --check