refactor: move buildable .NET source into src/, update CI/doc paths

Groups the repo root into src (buildable source), docs (already existed),
and everything else (db/, scripts/, tests/, deploy/ - deployment/ops/test
assets that aren't compiled, already organized as their own folders). CI
now only needs src/ to build: dotnet restore/build/test/publish all point
at src/TaxBaik.sln, src/TaxBaik.Web/, src/TaxBaik.Proxy/.

- git mv every project (Domain, Infrastructure, Application,
  Application.Tests, Web, Web.Client, Proxy) and TaxBaik.sln into src/ as a
  unit, so relative ProjectReference/.sln paths stay valid unchanged.
- .gitea/workflows/deploy.yml: 6 dotnet restore/clean/build/test/publish
  invocations now point at src/. db/migrations and scripts/ stay at root
  (deploy_gb.sh and browser-e2e.yml only touch published output and the
  deployed URL, not source paths - verified, no changes needed there).
- scripts/validate_admin_render.sh: admin render-mode file paths now
  src/TaxBaik.Web.Client/...
- scripts/validate_kst_timestamps.sh: dropped deploy.sh from its target
  list - that script was removed in the prior cleanup commit (dead, no
  CI workflow referenced it) but this validator still expected it to exist.
- CLAUDE.md, docs/ENGINEERING_HARNESS.md, docs/ADMIN_PATTERN_CRITIQUE_WBS.md:
  updated project-structure diagram, dotnet run/build commands, and grep
  targets to the new src/ paths (also fixed a pre-existing stale path in
  ADMIN_PATTERN_CRITIQUE_WBS.md that still said TaxBaik.Web/Components/Admin
  from before that ever moved to TaxBaik.Web.Client).
- Added a Repo Root harness rule + Architecture Guardrail entries: new files
  belong under src/docs/tests/scripts/db/deploy, not loose at root; temp
  work stays outside the repo (or under a gitignored .scratch/) and is
  never committed.

Verified locally: dotnet build/test src/TaxBaik.sln (26/26 tests), and all
three scripts/validate_*.sh pass against the new layout.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/TaxBaik.Web/Pages/Blog/Index.cshtml

@@ -0,0 +1,59 @@
+@page
+@model TaxBaik.Web.Pages.Blog.BlogIndexModel
+@{
+    ViewData["Title"] = "블로그 | 백원숙 세무회계";
+}
+
+<div class="container py-5">
+    <h1 class="fw-bold mb-5">세무 블로그</h1>
+
+    <!-- Category Tabs -->
+    <div class="mb-4 d-flex flex-wrap gap-2">
+        <a href="/taxbaik/blog" class="btn btn-sm @(Model.SelectedCategoryId == null ? "btn-primary" : "btn-outline-primary")">전체</a>
+        @foreach (var cat in Model.Categories)
+        {
+            <a href="/taxbaik/blog?categoryId=@cat.Id" class="btn btn-sm @(Model.SelectedCategoryId == cat.Id ? "btn-primary" : "btn-outline-primary")">@cat.Name</a>
+        }
+    </div>
+
+    <!-- Posts Grid -->
+    <div class="row g-4">
+        @foreach (var post in Model.Posts)
+        {
+            <div class="col-12 col-md-6 col-lg-4">
+                <div class="card h-100 border-0 shadow-sm">
+                    <div class="card-body">
+                        <small class="badge bg-primary">@post.CategoryName</small>
+                        <h5 class="card-title mt-2">@post.Title</h5>
+                        <p class="card-text small">@post.CreatedAt.ToString("yyyy-MM-dd")</p>
+                        <a href="/taxbaik/blog/@post.Slug" class="btn btn-sm btn-primary">글 내용 보기</a>
+                    </div>
+                </div>
+            </div>
+        }
+    </div>
+
+    <!-- Pagination -->
+    <nav aria-label="Page navigation" class="mt-5">
+        <ul class="pagination justify-content-center">
+            @if (Model.CurrentPage > 1)
+            {
+                <li class="page-item">
+                    <a class="page-link" href="/taxbaik/blog?page=@(Model.CurrentPage - 1)">이전</a>
+                </li>
+            }
+            @for (int i = 1; i <= Model.TotalPages; i++)
+            {
+                <li class="page-item @(i == Model.CurrentPage ? "active" : "")">
+                    <a class="page-link" href="/taxbaik/blog?page=@i">@i</a>
+                </li>
+            }
+            @if (Model.CurrentPage < Model.TotalPages)
+            {
+                <li class="page-item">
+                    <a class="page-link" href="/taxbaik/blog?page=@(Model.CurrentPage + 1)">다음</a>
+                </li>
+            }
+        </ul>
+    </nav>
+</div>