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/frontend/src/widgets/Header.tsx

@@ -10,13 +10,11 @@ import type { WsStatus } from "../shared/ws/socket";
 const titles: Record<DashboardTab, string> = {
   live: "Voice, Media & Recordings",
   messages: "Messages & Moderation",
-  analytics: "Analytics & Insights",
 };
 
 const subtitles: Record<DashboardTab, string> = {
   live: "Join voice channels, play media, stream audio, and browse recordings.",
   messages: "Capture, analyse, and moderate Discord messages.",
-  analytics: "Server moderation statistics and trends.",
 };
 
 interface HeaderProps {