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/lib/api/messages.ts

@@ -65,15 +65,6 @@ export const messagesApi = {
     );
   },
 
-  reanalyze: (id: string) =>
-    api.post<{ ok: boolean }>(`/api/messages/${id}/reanalyze`, {}),
-
-  reanalyzeBatch: (guildId?: string, channelId?: string) =>
-    api.post<{ ok: boolean; count: number }>("/api/messages/reanalyze-batch", {
-      guildId,
-      channelId,
-    }),
-
   search: (query: string, limit?: number) => {
     const params = new URLSearchParams({ q: query });
     if (limit) params.set("limit", String(limit));