🧹 chore(ci): establish dev integration governance

[seakee]

Summary

Establish the protected dev → main integration path while keeping main as the stable default branch. Community and maintenance work now has a documented PR target and main gains a source-identity gate.

Scope

• Frontend panel
• Manager Server
• CPA panel mode
• Full Docker mode
• Native packages / release
• Docs / Wiki
• CI / build / tooling

Changes

• Run existing PR validation and PR-template checks for pull requests and pushes involving dev.
• Add a main promotion workflow that accepts only seakee/CPA-Manager-Plus:dev as the PR source.
• Add CONTRIBUTING.md and PR-template guidance for the community dev integration path.

User Impact

Contributors submit changes to dev instead of directly to the stable main branch. Users continue to clone and browse the stable default branch.

Compatibility / Runtime Notes

• CPA panel mode: N/A.
• Manager Server mode: N/A.
• Full Docker / native packages: N/A.

Data / Security Notes

No runtime configuration, credentials, database data, or request data changes. The promotion workflow uses read-only GitHub Actions permissions and verifies both the source repository and branch.

Risk / Rollback

Risk level: Low

Rollback notes:

Revert this PR and remove the corresponding branch-protection rules if the integration policy must be withdrawn.

Verification

• Type check
• Lint
• Tests
• Build
• Manual UI check
• Docs/link check
• Not applicable, docs-only

Commands / evidence:

ruby -e 'require "yaml"; ...' .github/workflows/pr-check.yml .github/workflows/pr-template.yml .github/workflows/main-promotion.yml
npm run test  # 133 files, 1361 tests passed
git diff --check

Screenshots / Recordings

N/A — CI and contributor documentation only.

Docs

• README / README_CN updated for user-visible capabilities
• Matching docs manual and navigation updated
• Demo fixtures, screenshots, and deep links reviewed
• Release notes needed
• Not needed — added CONTRIBUTING.md is the canonical contribution guide; product documentation and release notes are unaffected.

Docs decision:

The change documents repository governance rather than a user-facing product capability.

Related

N/A