feat: implement admin inquiry create/edit/delete functionality

Core Components:
- Create reusable InquiryForm.razor component following SOLID principles
- Implement InquiryCreate.razor for registering new inquiries (offline, phone)
- Implement InquiryEdit.razor for modifying existing inquiries with delete
- Add DeleteAsync method to InquiryRepository and InquiryService
- Update InquiryList with 'Create' button and Edit link in table

Architecture:
- InquiryForm: Encapsulates form logic, can be reused for create/edit
- Service Layer: All operations go through InquiryService for cache invalidation
- Repository Pattern: Database operations isolated in InquiryRepository
- UI Consistency: Both pages follow admin-page-hero pattern

Features:
- Admin can create inquiries from phone/offline consultations
- Admin can modify inquiry details (name, phone, email, message, status, memo)
- Admin can delete inquiries with confirmation dialog
- All operations update dashboard cache
- Status validation and error handling throughout

Testing:
- Updated FakeInquiryRepository in tests to implement DeleteAsync

TaxBaik.Domain/Interfaces/IInquiryRepository.cs

@@ -16,4 +16,5 @@ public interface IInquiryRepository
     Task UpdateStatusAsync(int id, string status, CancellationToken cancellationToken = default);
     Task UpdateAdminMemoAsync(int id, string? adminMemo, CancellationToken cancellationToken = default);
     Task LinkClientAsync(int inquiryId, int clientId, CancellationToken cancellationToken = default);
+    Task DeleteAsync(int id, CancellationToken cancellationToken = default);
 }