feat: 用户 UUID 持久化与统一异常契约（Flyway baseline / UUIDv7 / 错误码透传）

- Flyway V1 baseline：identity 全部 5 表 + media.assets + platform 最小硬依赖（set_updated_at/regions），无 fixture 凭据；dev 种子独立为 afterMigrate 回调且默认不执行
- patbond-user 迁移到 PostgreSQL：UUIDv7 主键、JdbcClient 仓储、bcrypt 密码、唯一性依赖 DB 约束翻译为 409、E.164 手机号校验对齐 ck_users_phone
- 统一异常契约：common 新增 ErrorCode/BusinessException，两服务 GlobalExceptionHandler；auth 经 ApiErrorDecoder 原码透传下游错误，修复状态码折叠（审计 M1）
- 门禁：JAVA_HOME=jdk17 ./mvnw clean test，37 个测试 0 失败（含 Testcontainers postgres:16 集成测试），BUILD SUCCESS

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

patbond-user/pom.xml

@@ -35,11 +35,43 @@
             <groupId>org.springframework.security</groupId>
             <artifactId>spring-security-crypto</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-database-postgresql</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>runtime</scope>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-testcontainers</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.testcontainers</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>