feat(verification): add user identity verification system

Implement a complete user identity verification system with support for multiple identity types (student, teacher, staff, alumni). The system includes user-facing verification submission and status checking endpoints, admin endpoints for reviewing verification requests, middleware for protecting verification-required routes, and integration with the user model to track verification status.

internal/model/verification.go

@@ -0,0 +1,40 @@
+package model
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+	"gorm.io/gorm"
+)
+
+type VerificationRecord struct {
+	ID       string             `json:"id" gorm:"type:varchar(36);primaryKey"`
+	UserID   string             `json:"user_id" gorm:"type:varchar(36);index;not null"`
+	Identity UserIdentity       `json:"identity" gorm:"type:varchar(20);not null"`
+	Status   VerificationStatus `json:"status" gorm:"type:varchar(20);default:pending"`
+
+	RealName       string `json:"real_name" gorm:"type:varchar(100)"`
+	StudentID      string `json:"student_id" gorm:"type:varchar(50)"`
+	EmployeeID     string `json:"employee_id" gorm:"type:varchar(50)"`
+	Department     string `json:"department" gorm:"type:varchar(200)"`
+	ProofMaterials string `json:"proof_materials" gorm:"type:text"`
+
+	ReviewedAt   *time.Time `json:"reviewed_at" gorm:"type:timestamp"`
+	ReviewedBy   *string    `json:"reviewed_by" gorm:"type:varchar(36)"`
+	RejectReason string     `json:"reject_reason" gorm:"type:text"`
+
+	CreatedAt time.Time      `json:"created_at" gorm:"autoCreateTime"`
+	UpdatedAt time.Time      `json:"updated_at" gorm:"autoUpdateTime"`
+	DeletedAt gorm.DeletedAt `json:"-" gorm:"index"`
+}
+
+func (v *VerificationRecord) BeforeCreate(tx *gorm.DB) error {
+	if v.ID == "" {
+		v.ID = uuid.New().String()
+	}
+	return nil
+}
+
+func (VerificationRecord) TableName() string {
+	return "verification_records"
+}