The risk control center's moderation log records had no field for the
keyword that triggered a keyword block, so the admin UI couldn't show
which keyword was hit (only the application slog logged it).
- migration 156: add matched_keyword column to content_moderation_logs
- ContentModerationLog gains MatchedKeyword; set it on keyword block
- repo CreateLog/ListLogs persist and read the column
- frontend: show "命中关键词" inline in the log table and detail modal
- i18n: add matchedKeyword (zh/en)
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>