fix(ci): guard translated MDX repair scope

[hxy91819]

Summary

• add a dedicated MDX repair scope guard that snapshots pre-repair untracked locale files
• store the repair baseline in RUNNER_TEMP so the repair action cannot rewrite the trusted snapshot
• reject staged repair changes, non-locale tracked edits, and new untracked locale files while allowing translation-generated untracked locale pages from before repair

Verification

• python .github/scripts/i18n/tests/test_i18n_scripts.py
• python .github/scripts/i18n/workflow_shell_check.py --check-bash
• python .github/scripts/i18n/budget_check.py
• actionlint -color=false
• git diff --check
• autoreview clean: no accepted/actionable findings reported

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.