[changelog] Add changelog for v0.2.1

[github-actions]

Adds the CHANGELOG.md entry for the v0.2.1 stable release (published 2026-04-03).

Changes covered: 3 highlighted features + 6 other changes across 10 merged PRs, plus 4 new contributors.

Key highlights:

• Commands and UI elicitation support now lands in all four SDK languages (previously Node.js only)
• session.getMetadata across all SDKs
• sessionFs for virtualizing per-session storage in Node SDK
• Structured tool result fix (Node, Go, Python)
• Python: async context manager support, copilot.types removal, os.PathLike workspace_path
• Go: rpc API cleanup, SetModel signature fix

Note

🔒 Integrity filter blocked 2 items

The following items were blocked because they don't meet the GitHub integrity level.

• #970 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #475 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

Generated by Release Changelog Generator · ◷