fix: correct phone number formatting to follow standard pattern

- 10-digit numbers: XXXX-XXX-XXXX (4-3-3) - landline format
- 11-digit numbers: XXX-XXXX-XXXX (3-4-4) - mobile format

Apply consistent formatting on both frontend and backend.

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

src/TaxBaik.Application/Services/InquiryService.cs

@@ -160,8 +160,8 @@ public class InquiryService(
 
         return clean.Length switch
         {
-            10 => $"{clean[..3]}-{clean[3..6]}-{clean[6..]}",  // 01012345678 → 010-123-45678
-            11 => $"{clean[..3]}-{clean[3..7]}-{clean[7..]}",  // 010123456789 → 010-1234-56789
+            10 => $"{clean[..4]}-{clean[4..7]}-{clean[7..]}",  // 0089702448 → 0089-702-2448
+            11 => $"{clean[..3]}-{clean[3..7]}-{clean[7..]}",  // 01012345678 → 010-1234-5678
             _ => clean
         };
     }

src/TaxBaik.Web/Pages/Contact.cshtml

@@ -98,11 +98,13 @@
                 value = value.substring(0, 11); // 최대 11자리
             }
 
-            // 포맷팅: XXX-XXXX-XXXX 또는 XXX-XXX-XXXX
+            // 포맷팅
             if (value.length >= 10) {
                 if (value.length === 10) {
-                    value = `${value.substring(0, 3)}-${value.substring(3, 6)}-${value.substring(6)}`;
+                    // 10자리: XXXX-XXX-XXXX
+                    value = `${value.substring(0, 4)}-${value.substring(4, 7)}-${value.substring(7)}`;
                 } else if (value.length === 11) {
+                    // 11자리: XXX-XXXX-XXXX
                     value = `${value.substring(0, 3)}-${value.substring(3, 7)}-${value.substring(7)}`;
                 }
             } else if (value.length > 3) {