feat: S0 主键改雪花（DDL 去 identity + 实体 ASSIGN_ID + 雪花配置）

为什么：自增主键把 ID 分配锁在单库序列上，分库分表时无法横向扩展。趁线上业务数据
近零（只有系统种子表有量）先改，代价最低。

- sql/schema.sql、sql/schema-phase1.sql、sql/partition-maintenance.sql：61 处
  GENERATED BY DEFAULT AS IDENTITY 去掉，主键改 BIGINT 无默认值
- 52 个实体 @TableId IdType.AUTO -> IdType.ASSIGN_ID；两个入口 id-type: assign_id，
  并加 global-config.sequence.worker-id/datacenter-id（单机固定值，多实例需按实例分配）
- 新增 sql/migrate-s0-snowflake.sql：存量库幂等迁移，走 DROP IDENTITY 保留数据，不重建表
- 实测：三份建表脚本在新库连跑两遍幂等；线上 57 张表 identity 归零；
  watch_history/playback_ticket/order_event 的主键与唯一索引仍含分区键

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/AdminUser.java

@@ -14,7 +14,7 @@ import java.time.LocalDateTime;
 @TableName("sys_admin_user")
 public class AdminUser {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private String username;
     private String password;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/AdminUserRole.java

@@ -13,7 +13,7 @@ import lombok.NoArgsConstructor;
 @TableName("sys_admin_user_role")
 public class AdminUserRole {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private Long userId;
     private Long roleId;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/AuditLog.java

@@ -17,7 +17,7 @@ import java.time.LocalDateTime;
 @TableName("audit_log")
 public class AuditLog {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     /** ORDER / ENTITLEMENT / USER / CREATOR / PRICE */
     private String bizType;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/Menu.java

@@ -13,7 +13,7 @@ import java.time.LocalDateTime;
 @TableName("sys_menu")
 public class Menu {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private Long parentId;
     private String title;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/OperationLog.java

@@ -11,7 +11,7 @@ import java.time.LocalDateTime;
 @TableName("sys_operation_log")
 public class OperationLog {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private Long adminUserId;
     private String username;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/Permission.java

@@ -9,7 +9,7 @@ import lombok.Data;
 @TableName("sys_permission")
 public class Permission {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private String code;
     private String name;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/Role.java

@@ -14,7 +14,7 @@ import java.time.LocalDateTime;
 @TableName("sys_role")
 public class Role {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private String name;
     private String code;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/RoleCategory.java

@@ -14,7 +14,7 @@ import java.time.LocalDateTime;
 @TableName("sys_role_category")
 public class RoleCategory {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private String name;
     private String description;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/RoleMenu.java

@@ -13,7 +13,7 @@ import lombok.NoArgsConstructor;
 @TableName("sys_role_menu")
 public class RoleMenu {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private Long roleId;
     private Long menuId;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/RolePermission.java

@@ -13,7 +13,7 @@ import lombok.NoArgsConstructor;
 @TableName("sys_role_permission")
 public class RolePermission {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private Long roleId;
     private Long permissionId;

fruitshorts-module-system/src/main/java/com/fruitshorts/system/dal/entity/SysConfig.java

@@ -9,7 +9,7 @@ import lombok.Data;
 @TableName("sys_config")
 public class SysConfig {
 
-    @TableId(type = IdType.AUTO)
+    @TableId(type = IdType.ASSIGN_ID)
     private Long id;
     private String configKey;
     private String configValue;