Implement Redis rate limiting middleware for spam endpoints (FRE-4507)

- Add ioredis dependency to API package
- Create Redis connection utility (apps/api/src/config/redis.ts)
- Create Redis-backed spam rate limit middleware with per-minute and daily limits
- Create spam classification routes (SMS, number reputation, call analysis, feedback)
- Register middleware and routes in API server
- Add 7 passing tests for rate limit enforcement
- Update vitest config with required env vars

Co-Authored-By: Paperclip <noreply@paperclip.ing>

vitest.config.ts

@@ -7,6 +7,10 @@ export default defineConfig({
     deps: {
       interopDefault: true,
     },
+    env: {
+      HIYA_API_KEY: 'test-api-key',
+      HIYA_API_URL: 'https://api.hiya.com/v1',
+    },
   },
   optimizeDeps: {
     include: ['ws'],