feat: 新增 MCP 模块

- mcp_handler.go, mcp.go, mcp_repo.go, mcp_service.go

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

server/internal/repository/mcp_repo.go

@@ -0,0 +1,67 @@
+package repository
+
+import (
+	"x-agents/server/internal/model"
+
+	"gorm.io/gorm"
+)
+
+type MCPRepository struct {
+	db *gorm.DB
+}
+
+func NewMCPRepository(db *gorm.DB) *MCPRepository {
+	return &MCPRepository{db: db}
+}
+
+func (r *MCPRepository) DB() *gorm.DB {
+	return r.db
+}
+
+func (r *MCPRepository) Create(mcp *model.MCP) error {
+	return r.db.Create(mcp).Error
+}
+
+func (r *MCPRepository) FindAll() ([]model.MCP, error) {
+	var mcps []model.MCP
+	err := r.db.Order("created_at DESC").Find(&mcps).Error
+	return mcps, err
+}
+
+func (r *MCPRepository) FindByID(id string) (*model.MCP, error) {
+	var mcp model.MCP
+	err := r.db.First(&mcp, "id = ?", id).Error
+	if err != nil {
+		return nil, err
+	}
+	return &mcp, nil
+}
+
+func (r *MCPRepository) FindByName(name string) (*model.MCP, error) {
+	var mcp model.MCP
+	err := r.db.First(&mcp, "name = ?", name).Error
+	if err != nil {
+		return nil, err
+	}
+	return &mcp, nil
+}
+
+func (r *MCPRepository) FindByCategory(category string) ([]model.MCP, error) {
+	var mcps []model.MCP
+	err := r.db.Where("category = ?", category).Find(&mcps).Error
+	return mcps, err
+}
+
+func (r *MCPRepository) Update(mcp *model.MCP) error {
+	return r.db.Save(mcp).Error
+}
+
+func (r *MCPRepository) Delete(id string) error {
+	return r.db.Delete(&model.MCP{}, "id = ?", id).Error
+}
+
+func (r *MCPRepository) Count() (int64, error) {
+	var count int64
+	err := r.db.Model(&model.MCP{}).Count(&count).Error
+	return count, err
+}