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/api/src/domaincheck/dto/check-domain.dto.ts

@@ -1,8 +1,5 @@
 import {
-  ArrayMaxSize,
-  IsArray,
   IsNotEmpty,
-  IsOptional,
   IsString,
   Matches,
 } from 'class-validator';
@@ -16,19 +13,9 @@ import {
 export class CheckDomainDto {
   @IsString()
   @IsNotEmpty()
-  @Matches(/^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?$/, {
+  @Matches(/^[a-zA-Z0-9]([a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z]{2,})?$/, {
     message:
-      'Domain must be a valid label: alphanumeric and hyphens only, 1-63 characters, cannot start or end with a hyphen',
+      'Domain must be a valid label (e.g. "example") or full domain (e.g. "example.com")',
   })
   domain!: string;
-
-  /**
-   * Optional list of TLDs to check. If omitted, defaults are used.
-   * Per T-03-06: max 10 TLDs per request to prevent DoS.
-   */
-  @IsOptional()
-  @IsArray()
-  @IsString({ each: true })
-  @ArrayMaxSize(10, { message: 'Maximum 10 TLDs per request' })
-  tlds?: string[];
 }