refactor: atomic, DRY, and logging improvements across codebase

- Split llmModerationClient.ts (2170 lines) into 5 focused sub-modules
- Split aiAnalyzer.ts (1282 lines) into 4 modular pipelines
- Split messages.db.ts (826 lines) into 5 domain-specific modules
- Moved shared schema to @bete/shared, eliminated backend duplication
- Added createChildLogger to all voice-recording and AI moderation modules
- Extracted tryCommandThenFallback, normalizeMediaState, DEFAULT_VOICE_STATUS
- Created shared pagination.ts utility, eliminated 5+ cursor-pagination duplications
- Created shared messageMapper.ts for row mapping
- Standardized backend error handling with asyncHandler
- Added frontend createLogger utility and useAsyncAction hook
- Added structured logging to frontend hooks, socket, and API client

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/discord-gateway/src/modules/ai-moderation/severityDeriver.ts

@@ -0,0 +1,64 @@
+import { createChildLogger } from "@bete/shared/logger";
+import type { z } from "zod";
+import {
+  RecommendedActionSchema,
+  SeveritySchema,
+} from "./moderationSchemas.js";
+
+const log = createChildLogger("severityDeriver");
+
+/**
+ * Enhanced deferral detection pattern (R9).
+ *
+ * Only matches patterns where the model explicitly states it cannot make
+ * a decision and needs human review. Removed overly broad patterns that
+ * caused false positives:
+ * - "admin (perlu|harus|sebaiknya)" → common in regular sentences
+ * - "bisa (berpotensi|mengandung)" → decisive statements, not deferral
+ * - "maaf|sorry" → opinions/apologies, not deferral
+ * - "saya tidak yakin|tahu|paham" → expressing uncertainty, not deferral
+ */
+export const DEFERRAL_ANALYSIS_PATTERN =
+  /(?:kurang (?:konteks|bukti|informasi|data) (?:untuk (?:menilai|menentukan|memutuskan)|untuk moderasi)|perlu (?:dicek|diperiksa|ditinjau|dikaji|dievaluasi) (?:oleh )?(?:admin|moderator|manusia|human review)|tidak (?:bisa|dapat|mampu) (?:menentukan|menilai|memastikan|menyimpulkan|memberi keputusan|memoderasi).*(?:karena (?:konteks tidak jelas|informasi tidak cukup|bukti kurang|konteks kurang|tidak cukup konteks)|data tidak cukup|informasi tidak lengkap)|cannot determine|insufficient (?:context|evidence|information) (?:to |for )?(?:moderate|judge|evaluate|decide|classify)|(?:sepertinya|tampaknya) (?:perlu|harus) (?:ditinjau|diperiksa|dicek) (?:oleh )?(?:admin|moderator)|tidak cukup (?:bukti|informasi|konteks) (?:untuk (?:memberikan|membuat|menentukan)|memutuskan))/i;
+
+/**
+ * Exceptions: patterns that look like deferral but are actually decisive.
+ * Expanded to catch more variations where the model gives a clear verdict.
+ */
+export const DEFERRAL_EXCEPTION_PATTERN =
+  /tidak bisa menentukan.*(?:karena|sebab|dengan alasan|sebab tidak ada).*(?:clean|tidak (?:ada|terdapat|menunjukkan).*(?:pelanggaran|masalah|indikasi|konten)|aman|bersih|normal)/i;
+
+export function hasDeferralAnalysis(analysis: string): boolean {
+  if (DEFERRAL_EXCEPTION_PATTERN.test(analysis)) return false;
+  return DEFERRAL_ANALYSIS_PATTERN.test(analysis);
+}
+
+export function clampScore(value: number | undefined, fallback = 0): number {
+  return Math.max(
+    0,
+    Math.min(1, Number.isFinite(value) ? (value as number) : fallback),
+  );
+}
+
+export function deriveSeverity(
+  status: "clean" | "warn" | "flagged",
+  score: number,
+): z.infer<typeof SeveritySchema> {
+  if (status === "clean") return "none";
+  if (status === "warn") return score >= 0.65 ? "medium" : "low";
+  if (score >= 0.9) return "critical";
+  return score >= 0.75 ? "high" : "medium";
+}
+
+export function deriveRecommendedAction(
+  status: "clean" | "warn" | "flagged",
+  severity: z.infer<typeof SeveritySchema>,
+): z.infer<typeof RecommendedActionSchema> {
+  if (status === "clean") return "none";
+  if (status === "warn") return severity === "medium" ? "review" : "warn";
+  if (severity === "critical") return "escalate";
+  if (severity === "high") return "delete";
+  return "review";
+}
+
+log.debug("severityDeriver loaded");