refactor: 重构安全架构，提取通用安全模块到common-security

- 将JwtAuthenticationFilter、JwtUtil、JwtProperties从auth服务移至common-security模块
- 新增common-security通用安全模块，提供JWT认证、权限验证等核心安全功能
- 重命名SecurityConfiguration为AuthSecurityConfiguration，使用common-security的filter
- 新增JacksonConfiguration配置类，统一JSON序列化配置
- 新增头像更新功能AvatarUpdateRequestDTO
- 移除冗余的UserLoginResponseDTO类
- 更新各服务模块的依赖配置以引入common-security模块
- 新增README.md项目说明文档

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

aioj-backend-gateway/src/main/resources/application.yml

@@ -1,5 +1,5 @@
 server:
-  port: 8085
+  port: 18085
   error:
     include-stacktrace: never
 
@@ -25,6 +25,13 @@ spring:
                 - Path=/user-service/**
               filters:
                 - StripPrefix=1
+            # auth服务 Swagger 文档路由
+            - id: file-service-doc
+              uri: lb://file-service
+              predicates:
+                - Path=/file-service/**
+              filters:
+                - StripPrefix=1
             # auth业务接口
             - id: auth-service
               uri: lb://auth-service
@@ -50,6 +57,23 @@ spring:
                     backoff:
                       firstBackoff: 50ms
                       maxBackoff: 500ms
+            - id: file-service
+              uri: lb://file-service
+              predicates:
+                - Path=/api/v1/file/**
+              filters:
+                - name: Retry
+                  args:
+                    retries: 3
+                    statuses: BAD_GATEWAY,SERVICE_UNAVAILABLE
+                    backoff:
+                      firstBackoff: 50ms
+                      maxBackoff: 500ms
+            # 文件访问路由（公开，直接转发不去前缀）
+            - id: file-access
+              uri: lb://file-service
+              predicates:
+                - Path=/api/file/**
   # 设置应用启动后的就绪探针
   lifecycle:
     timeout-per-shutdown-phase: 30s