community: 20 contributor sprint kickoff

This is the public coordination issue for the 20-contributor sprint. Goal: make it easy for real external contributors to open useful, reviewable PRs. This is not a metric-inflation thread. Maintainer-authored PRs, bots, duplicate identities, and trivial PR splits do not count toward Claude for OSS evidence. Start here: - Sprint lanes: https://github.com/duct-tape2/ai-language-partner/blob/main/docs/community/CONTRIBUTOR_SPRINT.md - Good first issues: https://github.com/duct-tape2/ai-language-partner/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22 - First PR walkthrough: https://github.com/duct-tape2/ai-language-partner/blob/main/docs/community/FIRST_PR_WALKTHROUGH.md - Counting policy: https://github.com/duct-tape2/ai-language-partner/blob/main/docs/community/PR_REVIEW_AND_COUNTING_POLICY.md Useful contribution lanes: - Korean docs and learner notes - Japanese naturalness and beginner-safety review - Dialogue source content review - Expo / React Native accessibility - FastAPI and OpenAPI examples - Focused tests and repo checks - Release and maintainer process docs Maintainer promise: - First response target: within 24 hours when possible - No private context required for `good first issue` tasks - Docs and content-review PRs are welcome when they improve real learner or contributor experience - Every counted PR needs a human maintainer review comment before merge