feat: project skeleton + DB migrations V1-V12 + ga-common framework

- Gradle multi-module: ga-common, ga-core, ga-api, ga-batch, ga-admin
- Flyway V1-V12: org/product/rule/receive/ledger/settle/batch/code/menu/system + seed
- ga-common (complete):
  - model: ApiResponse, PageResponse, SearchParam, TreeNode
  - exception: ErrorCode, BizException, GlobalExceptionHandler
  - annotation + aop: @RequirePermission, @DataChangeLog, ApiLog
  - auth + security: JWT, SecurityConfig
  - mybatis: BaseMapper, EncryptTypeHandler, JsonTypeHandler, AuditInterceptor
  - code (Redis cached) / menu (RBAC tree) / file / system / notification
  - excel: SXSSF+Cursor export, SAX+batch import (1M/700K rows)
  - util: Date/Money/Mask/Encrypt/Security

ga-common/src/main/java/com/ga/common/annotation/DataChangeLog.java

@@ -0,0 +1,25 @@
+package com.ga.common.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * 데이터 변경 이력 자동 기록.
+ *
+ * <pre>
+ *   @DataChangeLog(menu = "RULE", table = "payout_rule")
+ *   public void updatePayoutRule(PayoutRuleVO vo) { ... }
+ * </pre>
+ *
+ * 동작: 메서드 실행 전·후의 대상 데이터를 비교 → data_change_log JSONB 컬럼에 저장.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface DataChangeLog {
+    String menu();
+    String table();
+    /** 액션 유형. 자동 추정 안 될 때 명시 */
+    String action() default "";
+}