Add semantic search to Copilot agent host sessions - #331836

PR classified as team-member.

✅ Head commit 2861c0c is signed by bhavyaus with trusted key B9E6CF327414C405989E950AC4305C2FE0554846 — approval requirement reduced from 2 to 1.

✅ Collaborator approvals: 1/1 (anthonykim1).

✅ No newly added runnable binary files.

✅ Engineering system changes are allowed.

• extensions/copilot/package.json

The PR author is a current VS Code team member.