feat(domaincheck): support all TLDs with suggestion alternatives

- Accept full domains (e.g. "example.xyz") not just labels
- Check the entered TLD as primary result
- Show .de, .com, .net, .org as alternative suggestions below
- Primary result highlighted with accent border
- Input without TLD still works (shows all 4 suggestions)
- Updated i18n placeholders and added "suggestions" label

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/app/(portal)/modules/domaincheck/actions.ts

@@ -1,16 +1,10 @@
-/**
- * Client-side action to check domain availability via the API.
- *
- * Calls POST /modules/domaincheck/check with the domain label.
- * Auth cookie is forwarded via credentials: 'include'.
- */
-
 const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3001';
 
 export interface DomainCheckResult {
   tld: string;
   fqdn: string;
   status: 'available' | 'registered';
+  primary: boolean;
 }
 
 export interface DomainCheckResponse {
@@ -18,13 +12,6 @@ export interface DomainCheckResponse {
   results: DomainCheckResult[];
 }
 
-/**
- * Check domain availability across TLD variants.
- *
- * @param domain - Base domain label (e.g., "example")
- * @returns Response with domain and results array
- * @throws Error if the API call fails
- */
 export async function checkDomainAction(
   domain: string,
 ): Promise<DomainCheckResponse> {