feat: add ads/sponsor/captcha modules and polish home & chat UI

backend/model/ad.go

@@ -0,0 +1,44 @@
+package model
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// 广告类型与状态
+const (
+	AdKindImage = "image"
+	AdKindText  = "text"
+
+	AdStatusPending  = "pending"
+	AdStatusActive   = "active"
+	AdStatusRejected = "rejected"
+	AdStatusExpired  = "expired"
+)
+
+// Ad 赞助广告（游客可申购，管理员审核后展示于首页侧栏）
+type Ad struct {
+	ID            uint           `gorm:"primaryKey" json:"id"`
+	Kind          string         `gorm:"size:16;not null;index" json:"kind"`     // image | text
+	Status        string         `gorm:"size:16;not null;index" json:"status"`   // pending/active/rejected/expired
+	ContactEmail  string         `gorm:"size:128;not null" json:"contact_email"`
+	LinkURL       string         `gorm:"size:512;not null" json:"link_url"`
+	ImageURL      string         `gorm:"size:512" json:"image_url"` // 图片广告
+	Title         string         `gorm:"size:64" json:"title"`      // 文字广告
+	TextColor     string         `gorm:"size:16" json:"text_color"`
+	BgColor       string         `gorm:"size:16" json:"bg_color"`
+	DurationDays  int            `gorm:"not null" json:"duration_days"`
+	PaymentID     string         `gorm:"size:64;not null" json:"payment_id"`
+	BuyerNote     string         `gorm:"size:200" json:"buyer_note"`
+	StartsAt      *time.Time     `json:"starts_at"`
+	EndsAt        *time.Time     `json:"ends_at"`
+	RejectReason  string         `gorm:"size:200" json:"reject_reason"`
+	SortOrder     int            `gorm:"not null;default:0" json:"sort_order"`
+	SubmitIP      string         `gorm:"size:45" json:"-"`
+	ReviewedAt    *time.Time     `json:"reviewed_at"`
+	ReviewedBy    *uint          `json:"reviewed_by"`
+	CreatedAt     time.Time      `json:"created_at"`
+	UpdatedAt     time.Time      `json:"updated_at"`
+	DeletedAt     gorm.DeletedAt `gorm:"index" json:"-"`
+}