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/membership/model/redeem_code.go

@@ -9,48 +9,55 @@ import (
 // MembershipRedeemCode 存储会员兑换码（只存 hash，不存明文 code）。
 type MembershipRedeemCode 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:"-"`
+	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:"-"`
 
 	// CodeHash 是 code 的 sha256(hex)；避免 DB 泄漏导致所有兑换码被直接使用。
-	CodeHash string `gorm:"size:64;uniqueIndex" json:"-"`
+	CodeHash string `gorm:"size:64;uniqueIndex;comment:兑换码哈希(sha256 hex)" json:"-"`
 	// CodeSuffix 用于展示/审计（例如最后 6 位）
-	CodeSuffix string `gorm:"size:16;index" json:"code_suffix"`
+	CodeSuffix string `gorm:"size:16;index;comment:兑换码后缀(展示/审计)" json:"code_suffix"`
 
-	Plan         string     `gorm:"size:30" json:"plan"`
-	DurationDays int        `json:"duration_days"`
-	ExpiresAt    *time.Time `json:"expires_at,omitempty"`
+	Plan         string     `gorm:"size:30;comment:会员套餐" json:"plan"`
+	DurationDays int        `gorm:"comment:有效天数(用于延长会员)" json:"duration_days"`
+	ExpiresAt    *time.Time `gorm:"comment:兑换码过期时间" json:"expires_at,omitempty"`
 
-	MaxUses  int `gorm:"default:1" json:"max_uses"`
-	UsedUses int `gorm:"default:0" json:"used_uses"`
+	MaxUses  int `gorm:"default:1;comment:最大可使用次数" json:"max_uses"`
+	UsedUses int `gorm:"default:0;comment:已使用次数" json:"used_uses"`
 
-	Status string `gorm:"size:20;default:active" json:"status"` // active/disabled
+	Status string `gorm:"size:20;default:active;comment:状态(active/disabled)" json:"status"`
 }
 
 func (MembershipRedeemCode) TableName() string {
 	return "membership_redeem_codes"
 }
 
+func (MembershipRedeemCode) TableComment() string {
+	return "会员兑换码"
+}
+
 type MembershipRedemption 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:"-"`
+	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:"-"`
 
-	MiniProgramID uint `gorm:"index:idx_redeem_user_date,priority:1" json:"mini_program_id"`
-	UserID        uint `gorm:"index:idx_redeem_user_date,priority:2" json:"user_id"`
+	MiniProgramID uint `gorm:"index:idx_redeem_user_date,priority:1;comment:小程序ID" json:"mini_program_id"`
+	UserID        uint `gorm:"index:idx_redeem_user_date,priority:2;comment:用户ID" json:"user_id"`
 
-	RedeemCodeID uint   `gorm:"index" json:"redeem_code_id"`
-	CodeSuffix   string `gorm:"size:16" json:"code_suffix"`
+	RedeemCodeID uint   `gorm:"index;comment:兑换码ID" json:"redeem_code_id"`
+	CodeSuffix   string `gorm:"size:16;comment:兑换码后缀(展示/审计)" json:"code_suffix"`
 
-	MembershipID uint `gorm:"index" json:"membership_id"`
+	MembershipID uint `gorm:"index;comment:会员记录ID" json:"membership_id"`
 
-	ClientIP  string `gorm:"size:64" json:"client_ip,omitempty"`
-	UserAgent string `gorm:"size:255" json:"user_agent,omitempty"`
+	ClientIP  string `gorm:"size:64;comment:客户端IP" json:"client_ip,omitempty"`
+	UserAgent string `gorm:"size:255;comment:User-Agent" json:"user_agent,omitempty"`
 }
 
 func (MembershipRedemption) TableName() string {
 	return "membership_redemptions"
 }
 
+func (MembershipRedemption) TableComment() string {
+	return "会员兑换流水"
+}