feat: 实现邮箱验证码和邮箱绑定功能

- 添加邮件发送服务实现(EmailService/EmailServiceImpl)
- 新增发送验证码、绑定邮箱、解绑邮箱接口
- 用户实体新增邮箱相关字段(userEmail/userEmailVerified)
- 添加邮件配置和JavaMailSender Bean
- 放行邮箱验证码接口(/v1/user/email/send-code)
- 新增ContextHolderUtils工具类用于获取当前用户上下文
- 完善Swagger文档注解

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

aioj-backend-common/aioj-backend-common-core/pom.xml

@@ -67,5 +67,11 @@
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-autoconfigure</artifactId>
         </dependency>
+        <!-- Spring Security (optional) -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-security</artifactId>
+            <optional>true</optional>
+        </dependency>
     </dependencies>
 </project>

aioj-backend-common/aioj-backend-common-core/src/main/java/cn/meowrain/aioj/backend/framework/core/utils/ContextHolderUtils.java

@@ -0,0 +1,87 @@
+package cn.meowrain.aioj.backend.framework.core.utils;
+
+import lombok.experimental.UtilityClass;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+/**
+ * Security Context 工具类
+ * 用于获取当前登录用户信息
+ */
+@Slf4j
+@UtilityClass
+public class ContextHolderUtils {
+
+	/**
+	 * 获取当前登录用户ID
+	 * @return 用户ID
+	 * @throws IllegalStateException 如果用户未登录
+	 */
+	public static Long getCurrentUserId() {
+		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+
+		if (authentication == null || !authentication.isAuthenticated()) {
+			throw new IllegalStateException("用户未登录");
+		}
+
+		String userId = authentication.getName();
+		try {
+			return Long.valueOf(userId);
+		}
+		catch (NumberFormatException e) {
+			log.error("解析用户ID失败: {}", userId, e);
+			throw new IllegalStateException("无效的用户ID");
+		}
+	}
+
+	/**
+	 * 获取当前登录用户ID（可选返回）
+	 * @return 用户ID，未登录返回 null
+	 */
+	public static Long getCurrentUserIdOrNull() {
+		try {
+			return getCurrentUserId();
+		}
+		catch (Exception e) {
+			return null;
+		}
+	}
+
+	/**
+	 * 获取当前登录用户角色
+	 * @return 用户角色，如 "USER", "ADMIN", "BAN"
+	 */
+	public static String getCurrentUserRole() {
+		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+
+		if (authentication == null || !authentication.isAuthenticated()) {
+			throw new IllegalStateException("用户未登录");
+		}
+
+		return authentication.getAuthorities()
+			.stream()
+			.findFirst()
+			.map(authority -> authority.getAuthority().replace("ROLE_", ""))
+			.orElse("USER");
+	}
+
+	/**
+	 * 判断当前用户是否已登录
+	 * @return true-已登录, false-未登录
+	 */
+	public static boolean isAuthenticated() {
+		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+		return authentication != null && authentication.isAuthenticated()
+				&& !"anonymousUser".equals(authentication.getName());
+	}
+
+	/**
+	 * 判断当前用户是否为管理员
+	 * @return true-是管理员, false-不是管理员
+	 */
+	public static boolean isAdmin() {
+		return "ADMIN".equals(getCurrentUserRole());
+	}
+
+}