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();
+}