Release v0.2.2 source and notes

[realproject7]

Summary

• Sync the published agentgather@0.2.2 version into the source tree.
• Add the v0.2.2 release notes and recorded verification results.
• This PR contains no feature changes beyond the already-published release source.

Verification

• pnpm build
• pnpm lint
• pnpm typecheck
• pnpm kit-guard
• pnpm no-stub
• pnpm test (396 passed, 0 failed)
• npm pack --dry-run --json
• Registry: agentgather@0.2.2 is published and tagged latest.

Release sequence

After this PR merges, tag the final main commit as v0.2.2, create the GitHub Release from docs/release-notes-v0.2.2.md, then close #219.

Closes #219

[realproject7]

Lead sign-off: CI is green, the final three-dot diff was independently inspected, and scope is limited to v0.2.2 source/version synchronization plus release notes. A sub-PO review was requested through the AG room, but no response arrived after two event waits; the operator directly instructed release closure, and that exception is recorded in the room. Proceeding with the final-main tag and GitHub Release sequence after merge.