docs: add Teams app legal pages

[GraceWalk]

Summary

• add Teams-specific privacy policy and terms of use pages in zh/en
• link the new legal pages from the Microsoft Teams integration docs
• document Teams data, permissions, storage, card actions, and support contacts for Store review

Validation

• node -e "JSON.parse(require('fs').readFileSync('docs.json','utf8')); console.log('docs.json ok')"
• git diff --check
• internal docs link existence check

Notes

• Local mint broken-links was not available because the mint command is not installed.
• The Teams app manifest in test-bot still needs to point privacyUrl and termsOfUseUrl at the new English pages before packaging.