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/backend/src/modules/analysis/analysis.schema.ts

@@ -0,0 +1,10 @@
+import { z } from "zod";
+
+export const searchQuerySchema = z.object({
+  q: z.string().default(""),
+  channelId: z.string().optional(),
+  guildId: z.string().optional(),
+  limit: z.coerce.number().int().positive().max(100).default(20),
+});
+
+export type SearchQuery = z.infer<typeof searchQuerySchema>;