chore(release): prepare v3.1.0 release (#7)

- Add comprehensive v3.1.0 changelog entry documenting all improvements
- Update version badge from 3.0.7 to 3.1.0 in README.md and README.zh.md

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

release: v3.0.8

feat: upgrade tech stack analysis (monorepo, rust, go, python)

📐 v3.0.6: Dynamic quality standards based on module complexity

🏗️ v3.0.5: Business domain hierarchy + deep documentation (400+ lines…

…, 5+ code examples)

📦 v3.0.4: Batch generation mechanism for quality optimization

✨ v3.0.3: Add quality check system (check_quality.py)

📦 v3.0.2: Update docs and rebuild mini-wiki.skill

Release v3.0.1: Documentation improvements

Release v3.0.0: Professional-Grade Documentation