feat: sam_stat P0 도메인 집계 구현 (Phase 2)

- 영업(Sales), 재무(Finance), 생산(Production) 3개 도메인 구현
- 일간/월간 통계 테이블 6개 마이그레이션 생성
- 도메인별 StatService (SalesStatService, FinanceStatService, ProductionStatService)
- Daily/Monthly 6개 Eloquent 모델 생성
- StatAggregatorService에 도메인 서비스 매핑 활성화
- StatJobLog duration_ms abs() 처리
- 스케줄러 등록 (일간 02:00, 월간 1일 03:00)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Models/Stats/StatJobLog.php

@@ -26,7 +26,7 @@ public function markRunning(): void
     public function markCompleted(int $recordsProcessed = 0): void
     {
         $durationMs = $this->started_at
-            ? (int) now()->diffInMilliseconds($this->started_at)
+            ? abs((int) now()->diffInMilliseconds($this->started_at))
             : null;
 
         $this->update([
@@ -40,7 +40,7 @@ public function markCompleted(int $recordsProcessed = 0): void
     public function markFailed(string $errorMessage): void
     {
         $durationMs = $this->started_at
-            ? (int) now()->diffInMilliseconds($this->started_at)
+            ? abs((int) now()->diffInMilliseconds($this->started_at))
             : null;
 
         $this->update([