feat: add comprehensive database models and type definitions

- Define Certificate model with full X.509 attributes
- Add CertificateAuthority model for CA management
- Implement CertificateRequest model for CSR handling
- Add CertificateRevocationList model for CRL support
- Define User and Organization models for access control
- Include comprehensive certificate type definitions (web, client, email, etc.)
- Add status enums for certificates, requests, and organizations
- Configure GORM relationships and constraints

models/csr.go

@@ -0,0 +1,50 @@
+package models
+
+import (
+	"time"
+
+	"github.com/google/uuid"
+	"gorm.io/gorm"
+)
+
+// CertificateRequest represents a request for a certificate (CSR)
+type CertificateRequest struct {
+	ID                     uuid.UUID       `json:"id" gorm:"type:uuid;primary_key;default:gen_random_uuid()"`
+	CommonName             string          `json:"common_name" gorm:"not null"`
+	SubjectAlternativeName string          `json:"subject_alternative_name"` // JSON array of SANs
+	Type                   CertificateType `json:"type" gorm:"not null"`
+	Status                 RequestStatus   `json:"status" gorm:"not null;default:'pending'"`
+	CertificateAuthorityID uuid.UUID       `json:"certificate_authority_id" gorm:"type:uuid;not null"`
+	RequesterName          string          `json:"requester_name" gorm:"not null"`
+	RequesterEmail         string          `json:"requester_email" gorm:"not null"`
+	RequesterPhone         string          `json:"requester_phone"`
+	Organization           string          `json:"organization"`
+	Department             string          `json:"department"`
+	City                   string          `json:"city"`
+	State                  string          `json:"state"`
+	Country                string          `json:"country"`
+	CSRFilePath            string          `json:"csr_file_path"` // Path to CSR file
+	CSRData                []byte          `json:"csr_data" gorm:"type:bytea"` // CSR data in DER format
+	ValidDays              int             `json:"valid_days" gorm:"not null;default:365"`
+	ApprovedBy             *uuid.UUID      `json:"approved_by" gorm:"type:uuid"`
+	ApprovedAt             *time.Time      `json:"approved_at"`
+	RejectionReason        string          `json:"rejection_reason"`
+	CreatedAt              time.Time       `json:"created_at" gorm:"autoCreateTime"`
+	UpdatedAt              time.Time       `json:"updated_at" gorm:"autoUpdateTime"`
+	DeletedAt              gorm.DeletedAt  `json:"deleted_at" gorm:"index"`
+
+	// Relationships
+	CertificateAuthority *CertificateAuthority `json:"certificate_authority" gorm:"foreignKey:CertificateAuthorityID"`
+	Certificates         []*Certificate        `json:"certificates" gorm:"foreignKey:RequestID"`
+}
+
+// TableName returns the table name for CertificateRequest
+func (cr *CertificateRequest) TableName() string {
+	return "certificate_requests"
+}
+
+// BeforeCreate generates a new UUID before creating the record
+func (cr *CertificateRequest) BeforeCreate(tx *gorm.DB) (err error) {
+	cr.ID = uuid.New()
+	return
+}