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/backend/src/shared/commandHelper.ts

@@ -0,0 +1,26 @@
+import type { CommandReply } from "@bete/shared";
+import { createChildLogger } from "@bete/shared/logger";
+import { publishCommand, readRedisStatus } from "./redis/index.js";
+
+export { createChildLogger };
+
+/**
+ * Attempt a Redis command first; if it fails or times out, fall back.
+ *
+ * @param commandFn  - Function that issues the publishCommand and returns the reply.
+ * @param fallbackFn - Async fallback, typically reads from Redis status key.
+ * @param commandLabel - Label used for logging (e.g. "voice:connect").
+ */
+export async function tryCommandThenFallback<T>(
+  commandFn: () => Promise<CommandReply<T> | null>,
+  fallbackFn: () => Promise<T>,
+  commandLabel: string,
+): Promise<T> {
+  const logger = createChildLogger(`command-helper:${commandLabel}`);
+  const reply = await commandFn();
+  if (reply?.success && reply.data !== undefined && reply.data !== null) {
+    return reply.data;
+  }
+  logger.warn("discord-gateway unreachable, falling back");
+  return fallbackFn();
+}

services/backend/src/shared/utils/messageMapper.ts

@@ -0,0 +1,57 @@
+// Shared message row mapper for backend repository modules
+
+export interface MappedMessage {
+  id: string;
+  guild_id: string;
+  channel_id: string;
+  thread_id: string | null;
+  user_id: string;
+  username: string;
+  avatar_url: string | null;
+  content: string;
+  edited_content: string | null;
+  created_at: number;
+  edited_at: number | null;
+  deleted_at: number | null;
+  type: string;
+  metadata: string | null;
+  ai_status: string | null;
+  ai_moderation_flags: string | null;
+  ai_moderation_score: number | null;
+  ai_analysis: string | null;
+  ai_categories: string | null;
+  ai_severity: string | null;
+  ai_confidence: number | null;
+  ai_recommended_action: string | null;
+  ai_analyzed_at: number | null;
+  ai_error: string | null;
+}
+
+export function mapMessageRow(row: Record<string, unknown>): MappedMessage {
+  return {
+    id: String(row.id ?? ""),
+    guild_id: String(row.guild_id ?? ""),
+    channel_id: String(row.channel_id ?? ""),
+    thread_id: (row.thread_id as string | null) ?? null,
+    user_id: String(row.user_id ?? ""),
+    username: String(row.username ?? ""),
+    avatar_url: (row.avatar_url as string | null) ?? null,
+    content: String(row.content ?? ""),
+    edited_content: (row.edited_content as string | null) ?? null,
+    created_at: Number(row.created_at ?? 0),
+    edited_at: (row.edited_at as number | null) ?? null,
+    deleted_at: (row.deleted_at as number | null) ?? null,
+    type: String(row.type ?? "text"),
+    metadata: (row.metadata as string | null) ?? null,
+    ai_status: (row.ai_status as string | null) ?? null,
+    ai_moderation_flags: (row.ai_moderation_flags as string | null) ?? null,
+    ai_moderation_score: (row.ai_moderation_score as number | null) ?? null,
+    ai_analysis: (row.ai_analysis as string | null) ?? null,
+    ai_categories: (row.ai_categories as string | null) ?? null,
+    ai_severity: (row.ai_severity as string | null) ?? null,
+    ai_confidence: (row.ai_confidence as number | null) ?? null,
+    ai_recommended_action: (row.ai_recommended_action as string | null) ?? null,
+    ai_analyzed_at: (row.ai_analyzed_at as number | null) ?? null,
+    ai_error: (row.ai_error as string | null) ?? null,
+  };
+}