refactor: replace dynamic imports with event bus pattern

Replace 12 dynamic `await import()` calls with domain events emitted
through the existing systemEvents bus, breaking circular dependencies
between services (economy/inventory/leveling -> quest, * -> dashboard).

- Add `emitAsync` to SystemEventEmitter for sequential listener awaiting,
  preserving DB transaction atomicity for quest progress tracking
- Add DOMAIN event constants (BALANCE_CHANGED, XP_GAINED, ITEM_COLLECTED,
  ITEM_USED, TRANSFER_COMPLETED, DAILY_CLAIMED, TRIVIA_*, EXAM_PASSED)
- Create shared/lib/eventWiring.ts to register all domain event listeners
- Convert quest event calls to `await systemEvents.emitAsync()` (5 calls)
- Convert dashboard event calls to `systemEvents.emit()` fire-and-forget (5 calls)
- Convert exam.service.ts userService import to static import (1 call)
- Convert dashboard.service.ts events import to static import (1 call)
- Leave inventory.service.ts validateAndExecuteEffect import unchanged (Task 3)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

shared/modules/dashboard/dashboard.service.ts

@@ -1,6 +1,7 @@
 import { DrizzleClient } from "@shared/db/DrizzleClient";
 import { users, transactions, moderationCases, inventory, lootdrops, items, type User } from "@db/schema";
 import { desc, sql, gte, eq } from "drizzle-orm";
+import { systemEvents, EVENTS } from "@shared/lib/events";
 import type { RecentEvent, ActivityData } from "./dashboard.types";
 import { TransactionType } from "@shared/lib/constants";
 
@@ -139,7 +140,6 @@ export const dashboardService = {
 
         // Broadcast to WebSocket clients
         try {
-            const { systemEvents, EVENTS } = await import("@shared/lib/events");
             systemEvents.emit(EVENTS.DASHBOARD.NEW_EVENT, {
                 ...fullEvent,
                 timestamp: (fullEvent.timestamp instanceof Date)