fix(moderation): remove manual reanalyze triggers — auto-recovery only

Manual per-message and batch reanalyze buttons/endpoints let anyone
re-queue arbitrary messages for LLM analysis, burning AI credits on
spam. Removed:
- FE: Reanalyze buttons in message list, search panel, and messages page
- FE: useReanalyze/useReanalyzeBatch hooks + messagesApi methods
- BE: POST /api/messages/:id/reanalyze and /reanalyze-batch endpoints
- BE: markForReanalysis/reanalyzeErrorBatch service+repository methods

Recovery of failed messages is fully automatic: the discord-gateway
startPendingAIAnalysisWorker retries 'pending' (batch path) and
'error/analysis_incomplete' (individual path) messages on
AI_ANALYSIS_RECOVERY_INTERVAL_MS.

services/frontend/src/hooks/index.ts

@@ -24,8 +24,6 @@ export {
   useMessages,
   useMessagesHasMore,
   useMessagesWsSync,
-  useReanalyze,
-  useReanalyzeBatch,
   useReview,
   useTextChannels,
 } from "./use-messages";