Add Chinese guidance for “不是……而是……”

[BrantonLiu]

Summary

• remove every “不是……而是……” construction from Chinese rewrites
• state the main point directly when the contrast adds nothing
• preserve a useful contrast with “区别于……” or move the negative point after the claim with “并非……”
• extend pattern 9 without changing the 35-pattern count

Checks

• python3 scripts/validate-package.py
• python3 skill-creator/scripts/quick_validate.py .
• npx --yes skills add . --list
• claude plugin validate .