docs(contributing): add maintainer routing map

[yeyitech]

Summary

• add contributor-facing maintainer routing guidance to the English and Chinese contributing guides
• document the module map, routing map, cross-module contacts, contribution-entry labels, and contributor growth path
• keep the guidance scoped to stable operational information instead of aspirational response SLAs

Closes #1082

Testing

• docs-only change; verified by reviewing final rendered markdown/diff

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 1082 - Fully compliant Compliant requirements: Add contributor-facing module map Add maintainer routing map List cross-module maintainers Document how to get help Define contribution-entry labels Outline contributor growth path Add guidance in both English and Chinese

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🏅 Score: 100

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ No major issues detected

[github-actions]

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