EsLint v9 (#154)

* Upgrade ESLint and related configurations to version 9

- Update ESLint to version 9.19.0
- Migrate ESLint configurations to flat config format
- Remove deprecated ESLint config files
- Update package dependencies and configurations
- Simplify ESLint setup across packages
- Remove unnecessary ESLint config blocks from package.json files
- Improved CI caching with Turborepo tasks
- Removed duplicate styles

packages/ui/src/makerkit/page.tsx

@@ -175,7 +175,10 @@ export function PageHeader({
 
           <If condition={description}>
             <If condition={displaySidebarTrigger}>
-              <Separator orientation="vertical" className="h-4 w-px hidden lg:block" />
+              <Separator
+                orientation="vertical"
+                className="hidden h-4 w-px lg:block"
+              />
             </If>
 
             <PageDescription>{description}</PageDescription>