경로 최적화: PathBase 제거 및 상대 경로로 전환

## 변경사항
- Program.cs: app.UsePathBase('/taxbaik') 제거
- Blazor 컴포넌트: /taxbaik/admin/* → ./* 상대 경로로 변경
- 모든 내부 링크 절대 경로 → 상대 경로로 전환

## 현황
✅ 빌드: 0 오류, 0 경고
✅ 헬스체크: HTTP 200
✅ 로그인 페이지: 로드 정상
❌ 로그인 API: 400 오류 (DB 오류 - 조사 중)

## 다음 단계
- LoginEndpoint에서 발생하는 DB 오류 원인 파악 필요
- Razor Pages 절대 경로도 상대 경로로 변경 (보류 중)

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

src/TaxBaik.Web.Client/Components/Admin/Pages/Clients/ClientDetail.razor

@@ -22,12 +22,12 @@
 <MudStack Row="true" AlignItems="AlignItems.Center" Class="mb-4" Spacing="2">
     <MudButton Variant="Variant.Outlined" Color="Color.Primary"
                StartIcon="@Icons.Material.Filled.ArrowBack"
-               @onclick="@(() => Navigation.NavigateTo("/taxbaik/admin/clients"))">
+               @onclick="@(() => Navigation.NavigateTo("./clients"))">
         목록으로
     </MudButton>
     <MudButton Variant="Variant.Outlined" Color="Color.Warning"
                StartIcon="@Icons.Material.Filled.Edit"
-               Href="@($"/taxbaik/admin/clients/{ClientId}/edit")">
+               Href="@($"./clients/{ClientId}/edit")">
         수정
     </MudButton>
 </MudStack>

src/TaxBaik.Web.Client/Components/Admin/Pages/Clients/ClientEdit.razor

@@ -13,7 +13,7 @@
 <PageTitle>@(Id.HasValue ? "고객 수정" : "고객 등록")</PageTitle>
 
 <AdminPageHeader Title="@(Id.HasValue ? "고객 수정" : "고객 등록")" Eyebrow="CRM">
-    <MudButton Variant="Variant.Outlined" Href="/taxbaik/admin/clients"
+    <MudButton Variant="Variant.Outlined" Href="./clients"
                StartIcon="@Icons.Material.Filled.ArrowBack">목록으로</MudButton>
 </AdminPageHeader>
 
@@ -81,7 +81,7 @@
                                OnClick="@SaveAsync" Disabled="@isSaving">
                         @(isSaving ? "저장 중..." : "저장")
                     </MudButton>
-                    <MudButton Variant="Variant.Outlined" Href="/taxbaik/admin/clients">
+                    <MudButton Variant="Variant.Outlined" Href="./clients">
                         취소
                     </MudButton>
                 </MudItem>
@@ -116,7 +116,7 @@
                 if (client is null)
                 {
                     Snackbar.Add("고객을 찾을 수 없습니다.", Severity.Error);
-                    Navigation.NavigateTo("/taxbaik/admin/clients");
+                    Navigation.NavigateTo("./clients");
                     return;
                 }
                 dto = new ClientFormModel
@@ -135,7 +135,7 @@
             catch (Exception ex)
             {
                 Snackbar.Add($"오류: {ex.Message}", Severity.Error);
-                Navigation.NavigateTo("/taxbaik/admin/clients");
+                Navigation.NavigateTo("./clients");
                 return;
             }
         }
@@ -188,7 +188,7 @@
                 else
                     Snackbar.Add("등록에 실패했습니다.", Severity.Error);
             }
-            Navigation.NavigateTo("/taxbaik/admin/clients");
+            Navigation.NavigateTo("./clients");
         }
         catch (Exception ex)
         {

src/TaxBaik.Web.Client/Components/Admin/Pages/Clients/ClientList.razor

@@ -14,7 +14,7 @@
     <ChildContent>
         <MudButton Variant="Variant.Filled" Color="Color.Primary"
                    StartIcon="@Icons.Material.Filled.PersonAdd"
-                   Href="/taxbaik/admin/clients/create">
+                   Href="./clients/create">
             고객 등록
         </MudButton>
     </ChildContent>
@@ -92,7 +92,7 @@
                         <td class="small">@c.CreatedAt.ToLocalTime().ToString("yy.MM.dd")</td>
                         <td>
                             <MudButtonGroup Size="Size.Small" Variant="Variant.Outlined">
-                                <MudButton @onclick="@(() => Navigation.NavigateTo($"/taxbaik/admin/clients/{c.Id}/edit"))">
+                                <MudButton @onclick="@(() => Navigation.NavigateTo($"./clients/{c.Id}/edit"))">
                                     수정
                                 </MudButton>
                                 <MudButton Color="Color.Error" @onclick="@(() => DeleteAsync(c))">