refactor: remove google/uuid from register_candidate.go

- IDs are now auto-generated by DB SERIAL columns
- No need to generate UUID in application code
- Let repository handle ID assignment from DB response
- Removed unused import

backend/internal/core/usecases/auth/register_candidate.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/google/uuid"
 	"github.com/rede5/gohorsejobs/backend/internal/core/domain/entity"
 	"github.com/rede5/gohorsejobs/backend/internal/core/dto"
 	"github.com/rede5/gohorsejobs/backend/internal/core/ports"
@@ -39,21 +38,21 @@ func (uc *RegisterCandidateUseCase) Execute(ctx context.Context, input dto.Regis
 	}
 
 	// 3. Create Candidate's Personal Tenant/Workspace
-	candidateTenantID := uuid.New().String()
+	// NOTE: ID is empty - will be auto-generated by DB (SERIAL)
 	candidateCompany := entity.NewCompany(
-		candidateTenantID,
+		"", // DB generates SERIAL id
 		fmt.Sprintf("Candidate - %s", input.Name),
 		nil, // No document for candidates
 		nil, // No contact - will use user's contact info
 	)
 
-	_, err = uc.companyRepo.Save(ctx, candidateCompany)
+	savedCompany, err := uc.companyRepo.Save(ctx, candidateCompany)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create candidate workspace: %w", err)
 	}
 
-	// 4. Create User Entity
-	user := entity.NewUser(uuid.New().String(), candidateTenantID, input.Name, input.Email)
+	// 4. Create User Entity - ID is auto-generated by DB
+	user := entity.NewUser("", savedCompany.ID, input.Name, input.Email)
 	user.PasswordHash = hashed
 
 	// Set Metadata
@@ -75,7 +74,7 @@ func (uc *RegisterCandidateUseCase) Execute(ctx context.Context, input dto.Regis
 		roles[i] = r.Name
 	}
 
-	// 4. Generate Token (Auto-login)
+	// 5. Generate Token (Auto-login)
 	token, err := uc.authService.GenerateToken(saved.ID, saved.TenantID, roles)
 	if err != nil {
 		return nil, err