feat: permitir a admins personalizar header desde landing pública

- Nuevo endpoint POST /companies/check-admin para verificar rol de admin
- Componente HeaderEditPopup con color pickers e image picker
- Botón flotante de editar sobre el header cuando el usuario es admin
- Popup tipo drawer inferior con formulario de personalización
- Reutiliza APIs existentes: companies/update y companies/upload-header

server/src/Models/Companies/Companies.Interface.ts

@@ -380,4 +380,5 @@ export interface ICompaniesManager {
     sysAdminUpdate(data: SysAdminUpdateCompanyParams): Promise<void>;
     sysAdminSetBanned(data: SysAdminSetCompanyBannedParams): Promise<void>;
     sysAdminGetInsights(data: SysAdminCompanyInsightsParams): Promise<SysAdminCompanyInsightsResult>;
+    checkCompanyAdmin(data: { companyId: string; sessionUser: string }): Promise<boolean>;
 }

server/src/Models/Companies/Companies.ts

@@ -1221,6 +1221,19 @@ class CompaniesManager implements ICompaniesManager {
             },
         };
     }
+
+    public async checkCompanyAdmin(data: { companyId: string; sessionUser: string }): Promise<boolean> {
+        const filterData =
+            data.companyId.indexOf("-") >= 0 ? { slug: data.companyId } : { _id: data.companyId };
+
+        const company = await this.companies.findOne(filterData as any);
+
+        if (!company) {
+            return false;
+        }
+
+        return await EmployeesList.checkPermission(company, data.sessionUser, EmployeeRoles.ADMIN);
+    }
 }
 
 const CompaniesList = new CompaniesManager();