refactor: comprehensive codebase cleanup and architecture hardening

- Sprint 1 (Quick Wins): Remove dead analytics modules, fix 4 unresolved
  imports, replace 3 console.warn with logger, remove mock-crc import
- Sprint 2 (Architecture): Create MascotChatRepository, AnalysisRepository,
  3 Zod schemas (mascot-chat, analysis, voice), deduplicate error classes,
  move 3 SQL queries from routes to repository
- Sprint 3 (Complexity): Replace 7 any types with proper interfaces,
  extract 6 helpers from prepareMediaMessage (CC 85 -> ~15)
- Sprint 4 (Config): Remove 22 dead env vars from .env, add 30 missing
  vars to .env.example, standardize naming

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

services/discord-gateway/src/modules/event-broadcaster/eventBroadcaster.ts

@@ -138,7 +138,7 @@ export class EventBroadcaster {
   async voicePcmData(
     pcmBuffer: Buffer,
     userId: string,
-    metadata?: any,
+    metadata?: Record<string, unknown>,
   ): Promise<void> {
     await this.publisher.publish("discord:voice:pcm", {
       type: "voice_pcm_data",