Add bilingual docs summaries

[Pigbibi]

Summary

• Add bilingual summary entry points to repository documentation.
• Keep existing detailed docs intact while adding Chinese or English summaries where missing.
• Add cross-language navigation for paired English / zh-CN docs where available.

Validation

• Custom bilingual coverage scan: coverage_issues=0.
• git diff --check passed.

Deployment note

Documentation-only change; no runtime code, secrets, production env, or deployment settings changed.

[Pigbibi]

Closing this PR because it was accidentally opened from a stale local CryptoLeaderRotation checkout that redirects to CryptoSnapshotPipelines. I will reopen the correct CryptoSnapshotPipelines documentation PR from the current repository worktree.