feat: 新增 Agent、Memory、Skill 模块

- handler: agent_handler, memory_handler, skill_handler
- model: agent.go, skill.go
- repository: agent_repo, skill_repo
- service: agent_service, memory_service, skill_service
- 新增 migrations 目录

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

server/internal/repository/skill_repo.go

@@ -0,0 +1,90 @@
+package repository
+
+import (
+	"x-agents/server/internal/model"
+
+	"gorm.io/gorm"
+)
+
+type SkillRepository struct {
+	db *gorm.DB
+}
+
+func NewSkillRepository(db *gorm.DB) *SkillRepository {
+	return &SkillRepository{db: db}
+}
+
+// DB 获取数据库连接
+func (r *SkillRepository) DB() *gorm.DB {
+	return r.db
+}
+
+func (r *SkillRepository) Create(skill *model.Skill) error {
+	return r.db.Create(skill).Error
+}
+
+func (r *SkillRepository) FindAll() ([]model.Skill, error) {
+	var skills []model.Skill
+	err := r.db.Order("skill_type, skill_name").Find(&skills).Error
+	return skills, err
+}
+
+func (r *SkillRepository) FindByID(id string) (*model.Skill, error) {
+	var skill model.Skill
+	err := r.db.First(&skill, "id = ?", id).Error
+	if err != nil {
+		return nil, err
+	}
+	return &skill, nil
+}
+
+func (r *SkillRepository) FindByType(skillType string) ([]model.Skill, error) {
+	var skills []model.Skill
+	err := r.db.Where("skill_type = ?", skillType).Order("skill_name").Find(&skills).Error
+	return skills, err
+}
+
+func (r *SkillRepository) FindByName(skillName string) (*model.Skill, error) {
+	var skill model.Skill
+	err := r.db.First(&skill, "skill_name = ?", skillName).Error
+	if err != nil {
+		return nil, err
+	}
+	return &skill, nil
+}
+
+func (r *SkillRepository) Update(skill *model.Skill) error {
+	return r.db.Save(skill).Error
+}
+
+func (r *SkillRepository) Delete(id string) error {
+	return r.db.Delete(&model.Skill{}, "id = ?", id).Error
+}
+
+// UpsertBatch 批量upsert skills
+func (r *SkillRepository) UpsertBatch(skills []model.Skill) error {
+	for _, skill := range skills {
+		var existing model.Skill
+		err := r.db.First(&existing, "skill_name = ? AND skill_type = ?", skill.SkillName, skill.SkillType).Error
+		if err == gorm.ErrRecordNotFound {
+			if err := r.db.Create(&skill).Error; err != nil {
+				return err
+			}
+		} else if err != nil {
+			return err
+		} else {
+			existing.SkillDesc = skill.SkillDesc
+			existing.Path = skill.Path
+			existing.Status = skill.Status
+			if err := r.db.Save(&existing).Error; err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+// DeleteByType 根据类型删除
+func (r *SkillRepository) DeleteByType(skillType string) error {
+	return r.db.Where("skill_type = ?", skillType).Delete(&model.Skill{}).Error
+}