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

apps/web/app/join/page.tsx

@@ -137,7 +137,7 @@ function InviteNotFoundOrExpired() {
         <Trans i18nKey={'teams:inviteNotFoundOrExpired'} />
       </Heading>
 
-      <p className={'text-sm text-muted-foreground'}>
+      <p className={'text-muted-foreground text-sm'}>
         <Trans i18nKey={'teams:inviteNotFoundOrExpiredDescription'} />
       </p>