feat: WBS-UX-03 FAQ 관리 기능 구현 — 어드민 CRUD + 홈페이지 DB 연동

DB:
- V007__CreateFaqs.sql: faqs 테이블 (question, answer, category,
  sort_order, is_active) + 기본 FAQ 4개 시드

Domain:
- Faq 엔티티
- IFaqRepository (GetActiveAsync, GetAllAsync, CRUD)

Infrastructure:
- FaqRepository: sort_order 정렬, CRUD

Application:
- FaqService: Categories 상수, Validate (질문·답변 필수)

Admin UI (Blazor):
- FaqList.razor: 전체 목록, 활성/비활성 상태 칩, 삭제 확인
- FaqEdit.razor: 질문/답변/카테고리/순서/활성 토글 폼
- MainLayout: 홈페이지 그룹 하위에 FAQ 관리 메뉴 추가

홈페이지:
- Index.cshtml 하드코딩 FAQ → ActiveFaqs DB 루프로 교체
- FAQ 없으면 섹션 전체 숨김 (빈 DB에 안전)
- IndexModel: FaqService 주입, Task.WhenAll 병렬 로드

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TaxBaik.Web/Components/Admin/Pages/Faqs/FaqEdit.razor

@@ -0,0 +1,133 @@
+@page "/admin/faqs/create"
+@page "/admin/faqs/{Id:int}/edit"
+@attribute [Authorize]
+@using TaxBaik.Application.Services
+@using TaxBaik.Domain.Entities
+@inject FaqService FaqService
+@inject NavigationManager Navigation
+@inject ISnackbar Snackbar
+
+<PageTitle>@(Id.HasValue ? "FAQ 수정" : "FAQ 등록")</PageTitle>
+
+<section class="admin-page-hero">
+    <div>
+        <MudText Typo="Typo.caption" Class="admin-eyebrow">홈페이지</MudText>
+        <MudText Typo="Typo.h4" Class="admin-page-title">@(Id.HasValue ? "FAQ 수정" : "FAQ 등록")</MudText>
+    </div>
+    <MudButton Variant="Variant.Outlined" Href="/taxbaik/admin/faqs"
+               StartIcon="@Icons.Material.Filled.ArrowBack">목록으로</MudButton>
+</section>
+
+<MudPaper Class="admin-surface" Elevation="0" Style="max-width:720px;">
+    @if (isLoading)
+    {
+        <MudProgressLinear Indeterminate="true" />
+    }
+    else
+    {
+        <MudForm @ref="form" @bind-IsValid="isValid">
+            <MudGrid Spacing="3">
+                <MudItem xs="12">
+                    <MudTextField @bind-Value="faq.Question"
+                                  Label="질문 *" Required="true"
+                                  RequiredError="질문을 입력하세요."
+                                  Counter="300" MaxLength="300"
+                                  Lines="2" AutoGrow="true"
+                                  Placeholder="예: 기장료가 얼마인지 미리 알 수 있나요?" />
+                </MudItem>
+                <MudItem xs="12">
+                    <MudTextField @bind-Value="faq.Answer"
+                                  Label="답변 *" Required="true"
+                                  RequiredError="답변을 입력하세요."
+                                  Lines="5" AutoGrow="true"
+                                  Placeholder="방문자에게 보여질 답변을 입력하세요." />
+                </MudItem>
+                <MudItem xs="12" md="6">
+                    <MudSelect @bind-Value="faq.Category" Label="카테고리" T="string" Clearable="true">
+                        @foreach (var cat in FaqService.Categories)
+                        {
+                            <MudSelectItem Value="@cat">@cat</MudSelectItem>
+                        }
+                    </MudSelect>
+                </MudItem>
+                <MudItem xs="12" md="3">
+                    <MudNumericField @bind-Value="faq.SortOrder"
+                                     Label="정렬 순서"
+                                     HelperText="작을수록 위에 노출"
+                                     Min="0" Max="9999" />
+                </MudItem>
+                <MudItem xs="12" md="3" Class="d-flex align-center">
+                    <MudSwitch T="bool" @bind-Value="faq.IsActive" Color="Color.Success"
+                               Label="@(faq.IsActive ? "노출 중" : "비활성")" />
+                </MudItem>
+
+                <MudItem xs="12" Class="d-flex gap-2 mt-2">
+                    <MudButton Variant="Variant.Filled" Color="Color.Primary"
+                               StartIcon="@Icons.Material.Filled.Save"
+                               OnClick="@SaveAsync" Disabled="@isSaving">
+                        @(isSaving ? "저장 중..." : "저장")
+                    </MudButton>
+                    <MudButton Variant="Variant.Outlined" Href="/taxbaik/admin/faqs">
+                        취소
+                    </MudButton>
+                </MudItem>
+            </MudGrid>
+        </MudForm>
+    }
+</MudPaper>
+
+@code {
+    [Parameter] public int? Id { get; set; }
+
+    private MudForm form = null!;
+    private Faq faq = new() { SortOrder = 10, IsActive = true };
+    private bool isValid;
+    private bool isLoading = true;
+    private bool isSaving;
+
+    protected override async Task OnInitializedAsync()
+    {
+        if (Id.HasValue)
+        {
+            var existing = await FaqService.GetByIdAsync(Id.Value);
+            if (existing is null)
+            {
+                Snackbar.Add("FAQ를 찾을 수 없습니다.", Severity.Error);
+                Navigation.NavigateTo("/taxbaik/admin/faqs");
+                return;
+            }
+            faq = existing;
+        }
+        isLoading = false;
+    }
+
+    private async Task SaveAsync()
+    {
+        await form.Validate();
+        if (!isValid) return;
+
+        isSaving = true;
+        try
+        {
+            if (Id.HasValue)
+            {
+                await FaqService.UpdateAsync(faq);
+                Snackbar.Add("FAQ가 수정되었습니다.", Severity.Success);
+            }
+            else
+            {
+                await FaqService.CreateAsync(faq);
+                Snackbar.Add("FAQ가 등록되었습니다.", Severity.Success);
+            }
+            Navigation.NavigateTo("/taxbaik/admin/faqs");
+        }
+        catch (Exception ex)
+        {
+            Snackbar.Add($"저장 실패: {ex.Message}", Severity.Error);
+        }
+        finally
+        {
+            isSaving = false;
+        }
+    }
+}