fix(rbac): Make role.slug NOT NULL to match DDL

- Updated role.entity.ts: slug is now required (NOT NULL)
- Updated rbac.service.ts: generate slug from code when creating roles
- Tenant entity already complete with all DDL fields (no changes needed)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/modules/rbac/entities/role.entity.ts

@@ -26,9 +26,9 @@ export class Role {
   @Index()
   code: string;
 
-  @Column({ type: 'varchar', length: 100, nullable: true })
+  @Column({ type: 'varchar', length: 100 })
   @Index()
-  slug: string | null;
+  slug: string;
 
   @Column({ type: 'text', nullable: true })
   description: string | null;

src/modules/rbac/services/rbac.service.ts

@@ -38,6 +38,7 @@ export class RbacService {
       tenant_id: tenantId,
       name: dto.name,
       code: dto.code,
+      slug: dto.code.toLowerCase().replace(/[^a-z0-9]+/g, '_'),
       description: dto.description || null,
       is_system: false,
       is_active: true,