feat: implement background job system with queue, worker, scheduler, and handlers

- Add job queue abstraction (InMemoryQueue and Redis/BullMQ adapter)
- Add polling worker with retry logic and exponential backoff
- Add 6 job handlers: darkwatch.scan, voiceprint.batch, hometitle.scan,
  removebrokers.process, reports.generate, notifications.send
- Add cron-based scheduler with tier-appropriate frequencies
  (Basic/Plus/Premium)
- Add tRPC scheduler router for admin (runJobNow, getJobStatus, etc.)
- Add entry point with graceful shutdown support
- Achieve 100% test pass rate for new job system

web/src/server/api/schemas/scheduler.ts

@@ -0,0 +1,19 @@
+import { object, string, optional, enumType } from "valibot";
+
+export const RunJobNowSchema = object({
+  type: string(),
+  payload: object({
+    userId: optional(string()),
+    subscriptionId: optional(string()),
+    requestId: optional(string()),
+    reportType: optional(string()),
+    reportScheduleId: optional(string()),
+    channel: optional(string()),
+    alertId: optional(string()),
+    jobId: optional(string()),
+  }),
+});
+
+export const JobStatusSchema = object({
+  jobId: string(),
+});