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.Client/Components/Admin/Pages/CommonCodes.razor

@@ -0,0 +1,138 @@
+@page "/admin/common-codes"
+@rendermode @(new InteractiveWebAssemblyRenderMode(prerender: false))
+@using TaxBaik.Web.Services.AdminClients
+@using TaxBaik.Domain.Entities
+@attribute [Authorize]
+@inject ICommonCodeBrowserClient CommonCodeClient
+@inject ISnackbar Snackbar
+
+<PageTitle>공통관리</PageTitle>
+
+<AdminPageHeader Title="공통관리" Eyebrow="System" Subtitle="공통코드 그룹과 항목을 일관된 기준으로 관리합니다." />
+
+<MudGrid Spacing="2">
+    <MudItem XS="12" MD="4">
+        <CommonCodeGroupPanel Groups="groups"
+                             SelectedGroup="selectedGroup"
+                             SelectedGroupChanged="OnGroupChanged"
+                             OnCreateRequested="PrepareCreate" />
+    </MudItem>
+
+    <MudItem XS="12" MD="8">
+        <CommonCodeListPanel Loading="@isLoading"
+                             Codes="codes"
+                             EditModel="editModel"
+                             IsCreateMode="isCreateMode"
+                             Form="form"
+                             EditRequested="EditCode"
+                             DeleteRequested="DeleteCode"
+                             SaveRequested="SaveCode"
+                             ResetRequested="PrepareCreate" />
+    </MudItem>
+</MudGrid>
+
+@code {
+    private List<string> groups = [];
+    private List<CommonCode> codes = [];
+    private string selectedGroup = "";
+    private bool isLoading = true;
+    private CommonCode editModel = new();
+    private bool isCreateMode = true;
+
+    protected override async Task OnInitializedAsync()
+    {
+        groups = await CommonCodeClient.GetGroupsAsync();
+        selectedGroup = groups.FirstOrDefault() ?? "";
+        await LoadCodes();
+        PrepareCreate();
+    }
+
+    private async Task OnGroupChanged(string value)
+    {
+        selectedGroup = value;
+        await LoadCodes();
+        PrepareCreate();
+    }
+
+    private async Task LoadCodes()
+    {
+        isLoading = true;
+        codes = string.IsNullOrWhiteSpace(selectedGroup)
+            ? []
+            : await CommonCodeClient.GetByGroupAsync(selectedGroup);
+        isLoading = false;
+    }
+
+    private void PrepareCreate()
+    {
+        isCreateMode = true;
+        editModel = new CommonCode
+        {
+            CodeGroup = selectedGroup,
+            IsActive = true
+        };
+    }
+
+    private void EditCode(CommonCode code)
+    {
+        isCreateMode = false;
+        editModel = new CommonCode
+        {
+            CodeGroup = code.CodeGroup,
+            CodeValue = code.CodeValue,
+            CodeName = code.CodeName,
+            SortOrder = code.SortOrder,
+            IsActive = code.IsActive
+        };
+    }
+
+    private async Task SaveCode()
+    {
+        editModel.CodeGroup = editModel.CodeGroup?.Trim() ?? string.Empty;
+        editModel.CodeValue = editModel.CodeValue?.Trim() ?? string.Empty;
+        editModel.CodeName = editModel.CodeName?.Trim() ?? string.Empty;
+
+        if (string.IsNullOrWhiteSpace(editModel.CodeGroup) ||
+            string.IsNullOrWhiteSpace(editModel.CodeValue) ||
+            string.IsNullOrWhiteSpace(editModel.CodeName))
+        {
+            Snackbar.Add("그룹, 값, 이름은 모두 입력해야 합니다.", Severity.Error);
+            return;
+        }
+
+        if (editModel.CodeGroup.Any(char.IsWhiteSpace))
+        {
+            Snackbar.Add("code_group에는 공백을 넣을 수 없습니다.", Severity.Error);
+            return;
+        }
+
+        if (editModel.CodeValue.Any(char.IsWhiteSpace))
+        {
+            Snackbar.Add("code_value에는 공백을 넣을 수 없습니다.", Severity.Error);
+            return;
+        }
+
+        if (!await CommonCodeClient.UpsertAsync(editModel))
+        {
+            Snackbar.Add("저장 실패", Severity.Error);
+            return;
+        }
+
+        Snackbar.Add("저장되었습니다.", Severity.Success);
+        await LoadCodes();
+        PrepareCreate();
+    }
+
+    private async Task DeleteCode(CommonCode code)
+    {
+        if (!await CommonCodeClient.DeleteAsync(code.CodeGroup, code.CodeValue))
+        {
+            Snackbar.Add("삭제 실패", Severity.Error);
+            return;
+        }
+
+        Snackbar.Add("삭제되었습니다.", Severity.Success);
+        await LoadCodes();
+        PrepareCreate();
+    }
+}