feat: Add public user information retrieval endpoint

- Introduced a new endpoint to fetch public user information without authentication.
- Implemented UserToPublicUserInfo function to format user data for the response.
- Updated UserService interface and user service implementation to support fetching users by username.
- Enhanced user handler to validate input parameters and check user status before responding.

internal/handler/user_handler.go

@@ -2,6 +2,7 @@ package handler
 
 import (
 	"carrotskin/internal/container"
+	"carrotskin/internal/model"
 	"carrotskin/internal/service"
 	"carrotskin/internal/types"
 
@@ -315,3 +316,55 @@ func (h *UserHandler) ResetYggdrasilPassword(c *gin.Context) {
 	h.logger.Info("Yggdrasil密码重置成功", zap.Int64("userId", userID))
 	RespondSuccess(c, gin.H{"password": newPassword})
 }
+
+// GetPublicInfo 获取用户公开信息
+// @Summary 获取用户公开信息
+// @Description 根据用户名或用户ID获取用户的公开信息（不包含敏感信息如邮箱）
+// @Tags user
+// @Accept json
+// @Produce json
+// @Param username query string false "用户名"
+// @Param id query int false "用户ID"
+// @Success 200 {object} model.Response{data=types.PublicUserInfo} "获取成功"
+// @Failure 400 {object} model.ErrorResponse "参数错误"
+// @Failure 404 {object} model.ErrorResponse "用户不存在"
+// @Router /api/v1/users/public [get]
+func (h *UserHandler) GetPublicInfo(c *gin.Context) {
+	username := c.Query("username")
+	idStr := c.Query("id")
+
+	// 至少需要提供一个参数
+	if username == "" && idStr == "" {
+		RespondBadRequest(c, "必须提供用户名或用户ID", nil)
+		return
+	}
+
+	var user *model.User
+	var err error
+
+	// 优先使用用户名查询
+	if username != "" {
+		user, err = h.container.UserService.GetByUsername(c.Request.Context(), username)
+	} else {
+		// 使用用户ID查询
+		id := parseIntWithDefault(idStr, 0)
+		if id == 0 {
+			RespondBadRequest(c, "无效的用户ID", nil)
+			return
+		}
+		user, err = h.container.UserService.GetByID(c.Request.Context(), int64(id))
+	}
+
+	if err != nil || user == nil {
+		RespondNotFound(c, "用户不存在")
+		return
+	}
+
+	// 检查用户状态
+	if user.Status != 1 {
+		RespondNotFound(c, "用户不可用")
+		return
+	}
+
+	RespondSuccess(c, UserToPublicUserInfo(user))
+}