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>
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