feat(providers): add CNB (cnb.cool) git provider

[Eyre921]

Summary

Adds a third GitProvider — CNB (cnb.cool) — alongside github and tgit, using the exact "thin class over a platform CLI" shape the TGit provider established. CNB's official CLI (@cnbcool/cnb-cli) already exposes everything the GitProvider interface needs, so this is mostly mechanical mirroring of the existing pattern.

A question for maintainers, up front: a provider is a permanent maintenance surface (every future interface change now lands in three providers). I'm opening this as a complete, live-tested implementation so the accept/decline decision is concrete rather than hypothetical — but if you'd rather not carry a CNB provider, feel free to close and I'll keep it in my fork. CNB is a Tencent-adjacent platform, so it may or may not be in scope for you.

Type of Change

• New feature (non-breaking change that adds functionality)

How each interface method maps to the CNB CLI

GitProvider	CNB CLI
authenticate / isAuthenticated	cnb login (OAuth2 device flow) + cnb status
cloneRepo	git clone with token, or cnb git-credential helper
createPullRequest	cnb pulls post-pull
createRepo	cnb repositories create-repo
username	cnb users get-user-info (or CNB_USERNAME)

Auth mirrors the GitHub provider's dual path: interactive cnb login on a dev machine, or a CNB_TOKEN env var for headless/CI use (no login step) — the same idea as GITHUB_TOKEN.

Wiring: registry.ts maps cnb.cool / cnb.woa.com hosts to the provider and registers it in the factory. No behavior changes for existing providers.

Test Plan

• npx tsc --noEmit, npm run build
• npx vitest run — 142 files, 1751 tests; 6 new in cnb-provider.test.ts (host detection, factory, repo-input parsing incl. nested group paths)
• Live end-to-end against real cnb.cool (token in env), driving the wrapper functions: createRepo → cloneRepo → push main + feature → createPullRequest → delete-repo cleanup. The PR URL came back https://cnb.cool/<owner>/<repo>/-/pulls/1.

Two bugs the live run surfaced (and this PR fixes) — build alone didn't catch them:

• cnbWhoami() returned the CNB_USERNAME credential placeholder ("cnb") instead of the real account; now parses username: from the API first.
• the CLI prints YAML, not JSON, so username / PR-URL parsing is regex-based rather than JSON.parse.

Notes for Reviewers

• The live E2E is intentionally not committed as a CI test: it needs a CNB_TOKEN secret and creates/deletes a real repo. Only the pure unit tests run in CI. Happy to add a gated e2e test (behind CNB_TOKEN, self-cleaning) if you want one in the suite.
• No new runtime dependency — the provider shells out to the cnb CLI, exactly as tgit shells out to gf. ensureInstalled() installs it via npm i -g @cnbcool/cnb-cli when missing.
• getDefaultProvider() is untouched: CNB is only selected by explicit cnb.cool host, never as a fallback.

[jeff-r2026]

Thanks for the thorough implementation and the live-tested E2E — the spawnSync-with-args design, the assertCnbApiOk guard for the "CLI exits 0 but API returned 4xx" case, and the cnbWhoami API-first parsing are all solid.

One blocker before this can merge, per our docs-sync convention (see CLAUDE.md): adding a user-selectable provider is an observable behavior change, so the docs need to be updated in the same PR. Right now the PR touches no documentation. Please update:

• docs/providers.md — add a cnb row to the platform table (host cnb.cool / cnb.woa.com, auth via cnb login or CNB_TOKEN), and add the detection rules (https://cnb.cool/o/r → cnb, git@cnb.cool:o/r.git → cnb).
• docs/usage-guide.md — the provider: field in the teamai.yaml section currently only documents github/tgit; please mention cnb as a valid value.
• Keep the bilingual pair in sync: mirror the same changes into docs/usage-guide.zh-CN.md (and any zh-CN counterpart of providers.md if one exists).

While updating the guide, please also call out the current capability gap: fetchMergeRequest and listOrgRepos are not implemented for CNB, so a CNB repo can be cloned / created / opened-as-PR but can't yet drive teamai ci extract-mr or org-repo listing. Documenting this avoids users assuming CNB is at full parity with tgit.

The accept/decline call on carrying a third provider is for the maintainers, but getting the docs in now makes it a complete, mergeable PR either way. Thanks!