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/service/memory_service.go

@@ -0,0 +1,50 @@
+package service
+
+import (
+	"x-agents/server/internal/repository"
+
+	"x-agents/server/internal/model"
+)
+
+// MemoryService 记忆服务
+type MemoryService struct {
+	agentRepo *repository.AgentRepository
+}
+
+// NewMemoryService 创建记忆服务
+func NewMemoryService(agentRepo *repository.AgentRepository) *MemoryService {
+	return &MemoryService{
+		agentRepo: agentRepo,
+	}
+}
+
+// CreateMemory 创建记忆
+func (s *MemoryService) CreateMemory(agentID, userID, content, memoryType string, importance int) (*model.AgentMemory, error) {
+	memory := &model.AgentMemory{
+		AgentID:    agentID,
+		UserID:     userID,
+		Content:    content,
+		MemoryType: memoryType,
+		Importance: importance,
+	}
+
+	err := s.agentRepo.CreateMemory(memory)
+	if err != nil {
+		return nil, err
+	}
+
+	return memory, nil
+}
+
+// GetMemories 获取记忆列表
+func (s *MemoryService) GetMemories(agentID string, userID string, limit int) ([]model.AgentMemory, error) {
+	if userID != "" {
+		return s.agentRepo.FindMemoriesByUserID(agentID, userID, limit)
+	}
+	return s.agentRepo.FindMemoriesByAgentID(agentID, limit)
+}
+
+// DeleteMemory 删除记忆
+func (s *MemoryService) DeleteMemory(memoryID string) error {
+	return s.agentRepo.DeleteMemory(memoryID)
+}