feat: 新增Model管理模块

- 添加 Model 实体定义
- 实现 Model CRUD 接口
- 添加 Model 仓储层和服务层

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

server/internal/model/model_info.go

@@ -0,0 +1,69 @@
+package model
+
+import "time"
+
+// ModelInfo 模型信息
+type ModelInfo struct {
+	ID          string    `json:"id" gorm:"primaryKey;type:varchar(36)"`
+	Name        string    `json:"name" gorm:"type:varchar(255);not null"`
+	ModelType   string    `json:"model_type" gorm:"type:varchar(50);not null"` // chat/embedding/rerank/vlm
+	Provider    string    `json:"provider" gorm:"type:varchar(50);not null"`    // OpenAI/Ollama
+	Model       string    `json:"model" gorm:"type:varchar(255);not null"`      // 模型标识
+	APIKey      string    `json:"api_key" gorm:"type:text"`                    // API 密钥
+	BaseURL     string    `json:"base_url" gorm:"type:varchar(500)"`            // 基础 URL
+	APIEndpoint string    `json:"api_endpoint" gorm:"type:varchar(500)"`        // API 端点路径
+	Status      string    `json:"status" gorm:"type:varchar(20);default:active"` // active/inactive
+	CreatedAt   time.Time `json:"created_at"`
+	UpdatedAt   time.Time `json:"updated_at"`
+}
+
+func (ModelInfo) TableName() string {
+	return "model_info"
+}
+
+// ModelListRequest 获取模型列表请求
+type ModelListRequest struct {
+}
+
+// ModelListResponse 获取模型列表响应
+type ModelListResponse struct {
+	List []ModelInfo `json:"list"`
+}
+
+// CreateModelRequest 创建模型请求
+type CreateModelRequest struct {
+	Name        string `json:"name" binding:"required"`
+	ModelType   string `json:"model_type" binding:"required"`
+	Provider    string `json:"provider" binding:"required"`
+	Model       string `json:"model" binding:"required"`
+	APIKey      string `json:"api_key" binding:"required"`
+	BaseURL     string `json:"base_url" binding:"required"`
+	APIEndpoint string `json:"api_endpoint"`
+}
+
+// UpdateModelRequest 更新模型请求
+type UpdateModelRequest struct {
+	Name        string `json:"name"`
+	ModelType   string `json:"model_type"`
+	Provider    string `json:"provider"`
+	Model       string `json:"model"`
+	APIKey      string `json:"api_key"`
+	BaseURL     string `json:"base_url"`
+	APIEndpoint string `json:"api_endpoint"`
+	Status      string `json:"status"`
+}
+
+// TestModelRequest 测试模型连接请求
+type TestModelRequest struct {
+	Provider    string `json:"provider" binding:"required"`
+	Model       string `json:"model" binding:"required"`
+	APIKey      string `json:"api_key" binding:"required"`
+	BaseURL     string `json:"base_url" binding:"required"`
+	APIEndpoint string `json:"api_endpoint"`
+}
+
+// TestModelResponse 测试模型连接响应
+type TestModelResponse struct {
+	Success bool   `json:"success"`
+	Message string `json:"message"`
+}