fix(ai-moderation): bedah delay attachment ~330s -> target <20s

Root cause (trace msg 1541417073245290638):
- Race-guard upload-pending balik results:[] diperlakukan sbg SUKSES
  -> row yatam 'processing' sampai cleanup 300s mengembalikan
- Vision gagal 3x utk GIF besar (SSE truncation) tanpa fallback

Fix:
- Sinyal eksplisit uploadPending dari worker race guard
- Classifier murni classifyIndividualWorkerResult(): upload_pending ->
  requeue pending + reschedule segera (250ms), bukan error palsu;
  empty-results ok:true kini error transien (bug silent-success mati)
- llmVision fallback stream:false sekali saat SSE truncation
- Safety-net cleanup stuck processing 300s -> 120s

services/discord-gateway/src/modules/message-capture/messagesCleanup.ts

@@ -48,7 +48,13 @@ export class MessagesCleanup {
   }
 
   async revertStuckProcessingMessages(
-    timeoutMs: number = 300000,
+    // 2026-08-24: lowered from 300000 — this cleanup is the last-resort
+    // recoverer for rows stuck in `processing`. With the upload-pending
+    // race-guard now requeueing properly (fallbackResultClassifier), any row
+    // that still sits here for >2min is a genuine leak; reverting sooner
+    // bounds the worst-case delay without racing legitimate in-flight work
+    // (media batches can legitimately take ~60s+).
+    timeoutMs: number = 120000,
   ): Promise<number> {
     this.logger.debug({ timeoutMs }, "revertStuckProcessingMessages entry");
     try {