feat(cli): standardize inject workflow and add multilingual README

[baekho-lim]

Summary

• add selective inject options (--only, --only-env, --all, --dry-run) while keeping legacy default compatibility
• optimize pre-auth so it only runs for targeted biometric secrets
• refresh docs and troubleshooting for repeated prompt root cause and recommended --only usage
• add multilingual root READMEs (ko, ja, zh-CN, fr, de) with language selector and i18n sync governance
• add commit-standard workflow and i18n drift check in CI

Validation

• ./scripts/check-readme-i18n.sh
• swift build -c release
• ./scripts/test-full.sh