Enhance database models with comments and table descriptions

- Added comments to various fields in the database models for better clarity and understanding.
- Implemented TableComment methods for several models to provide descriptive information about their purpose.
- Updated the AutoMigrate function to support setting table comments in the database.
- Improved overall documentation within the code to facilitate future maintenance and development.

internal/model/product.go

@@ -7,20 +7,24 @@ import (
 )
 
 type Product struct {
-	ID          uint           `gorm:"primarykey" json:"id"`
-	CreatedAt   time.Time      `json:"created_at"`
-	UpdatedAt   time.Time      `json:"updated_at"`
-	DeletedAt   gorm.DeletedAt `gorm:"index" json:"-"`
+	ID        uint           `gorm:"primarykey;comment:商品ID" json:"id"`
+	CreatedAt time.Time      `gorm:"comment:创建时间" json:"created_at"`
+	UpdatedAt time.Time      `gorm:"comment:更新时间" json:"updated_at"`
+	DeletedAt gorm.DeletedAt `gorm:"index;comment:删除时间" json:"-"`
 
-	Name        string  `gorm:"size:200;not null" json:"name"`
-	Description string  `gorm:"type:text" json:"description"`
-	Price       float64 `gorm:"type:decimal(10,2);not null" json:"price"`
-	Stock       int     `gorm:"default:0" json:"stock"`
-	ImageURL    string  `gorm:"size:500" json:"image_url"`
-	Category    string  `gorm:"size:50" json:"category"`
-	Status      int     `gorm:"default:1" json:"status"`
+	Name        string  `gorm:"size:200;not null;comment:商品名" json:"name"`
+	Description string  `gorm:"type:text;comment:商品描述" json:"description"`
+	Price       float64 `gorm:"type:decimal(10,2);not null;comment:价格" json:"price"`
+	Stock       int     `gorm:"default:0;comment:库存" json:"stock"`
+	ImageURL    string  `gorm:"size:500;comment:图片URL" json:"image_url"`
+	Category    string  `gorm:"size:50;comment:分类" json:"category"`
+	Status      int     `gorm:"default:1;comment:状态(1上架/0下架)" json:"status"`
 }
 
 func (Product) TableName() string {
 	return "products"
 }
+
+func (Product) TableComment() string {
+	return "商品"
+}