fix: simplify phone number validation to accept any 10-11 digit format

- Remove restrictive '01X' prefix requirement
- Accept any valid 10-11 digit phone number
- Auto-format to XXX-XXX-XXXX pattern on backend
- Now accepts: 0089702448, 01012345678, 010-1234-5678, etc

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/TaxBaik.Application/Services/InquiryService.cs

@@ -12,7 +12,7 @@ public class InquiryService(
     IInquiryNotificationService notificationService,
     IMemoryCache memoryCache)
 {
-    private static readonly Regex PhoneRegex = new(@"^01[0-9]\d{7,8}$");
+    private static readonly Regex PhoneRegex = new(@"^\d{10,11}$");
 
     public async Task<int> SubmitAsync(
         string name, string phone, string serviceType, string message,