feat: 更新后端skill服务

- 更新 skill_handler.go handler层
- 更新 skill.go model层
- 更新 skill_repo.go repository层
- 更新 skill_service.go service层
- 更新 main.go 入口文件

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/repository/skill_repo.go

@@ -53,8 +53,25 @@ func (r *SkillRepository) FindByName(skillName string) (*model.Skill, error) {
 	return &skill, nil
 }
 
+// Update 更新技能（只更新传入的字段）
 func (r *SkillRepository) Update(skill *model.Skill) error {
-	return r.db.Save(skill).Error
+	updates := make(map[string]interface{})
+	if skill.SkillName != "" {
+		updates["skill_name"] = skill.SkillName
+	}
+	if skill.SkillDesc != "" {
+		updates["skill_desc"] = skill.SkillDesc
+	}
+	if skill.SkillType != "" {
+		updates["skill_type"] = skill.SkillType
+	}
+	if skill.Status != "" {
+		updates["status"] = skill.Status
+	}
+	if skill.Path != "" {
+		updates["path"] = skill.Path
+	}
+	return r.db.Model(&model.Skill{}).Where("id = ?", skill.ID).Updates(updates).Error
 }
 
 func (r *SkillRepository) Delete(id string) error {