fix(admin): reduce crm mudblazor interop

src/TaxBaik.Web.Client/Components/Admin/Pages/Contracts.razor

@@ -117,15 +117,23 @@ else
                     }
                 </div>
                 <MudForm @ref="form">
-                    <MudSelect T="int?" @bind-Value="contractForm.ClientId" Label="고객" Required="true" Variant="Variant.Outlined" FullWidth="@true" Class="mb-3" RequiredError="고객을 선택하세요." Disabled="@isEditMode">
-                        @foreach (var client in clients)
-                        {
-                            <MudSelectItem Value="@((int?)client.Id)">@GetClientDisplayName(client)</MudSelectItem>
-                        }
-                    </MudSelect>
+                    <div class="mb-3">
+                        <label class="mud-input-label mud-input-label-animated mud-input-label-outlined mb-1">고객</label>
+                        <select class="mud-input mud-input-outlined mud-input-root mud-input-root-adorned-start"
+                                style="width: 100%; min-height: 56px; padding: 16px 14px;"
+                                value="@(contractForm.ClientId?.ToString() ?? string.Empty)"
+                                disabled="@isEditMode"
+                                @onchange="e => contractForm.ClientId = int.TryParse(e.Value?.ToString(), out var clientId) ? clientId : null">
+                            <option value="">고객을 선택하세요.</option>
+                            @foreach (var client in clients)
+                            {
+                                <option value="@client.Id">@GetClientDisplayName(client)</option>
+                            }
+                        </select>
+                    </div>
                     <MudTextField T="string" @bind-Value="contractForm.ContractNumber" Label="계약번호" Variant="Variant.Outlined" FullWidth="@true" Class="mb-3" Required="true" />
                     <CommonCodeSelect @bind-Value="contractForm.ServiceType" Group="CONTRACT_SERVICE_TYPE" Label="서비스 유형" Class="mb-3" Required="true" />
-                    <MudDatePicker @bind-Date="contractForm.StartDate" Label="계약 시작일" Variant="Variant.Outlined" FullWidth="@true" Class="mb-3" Required="true" />
+                    <MudTextField T="string" Label="계약 시작일" Variant="Variant.Outlined" FullWidth="@true" Class="mb-3" Required="true" Value="@(contractForm.StartDate?.ToString("yyyy-MM-dd") ?? string.Empty)" />
                     <MudNumericField T="decimal?" @bind-Value="contractForm.MonthlyFee" Label="월 수수료" Variant="Variant.Outlined" FullWidth="@true" Class="mb-4" />
                     
                     <div class="d-flex justify-end gap-2">