fix(deploy.yml): Replace problematic find -delete with robust rm/mkdir/cp pattern

ROOT CAUSE OF CI/CD DEPLOYMENT FAILURE:
Line 48 used: find ../src/KArtSell.Host/wwwroot -mindepth 1 -delete
This fails because:
1. Directory may not exist
2. find -delete has permission issues in CI environment
3. No mkdir to create directory if missing

SOLUTION:
Replace with same pattern as deploy-working ci.yml:
  cd ..
  rm -rf src/KArtSell.Host/wwwroot
  mkdir -p src/KArtSell.Host/wwwroot
  cp -r frontend/dist/* src/KArtSell.Host/wwwroot/

This is portable, reliable, and works in all CI/CD environments.

Also updated .gitignore to ignore entire wwwroot directory
to prevent git ownership conflicts.

This fixes the persistent "Build frontend into Host static assets" failure.

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

.gitea/workflows/deploy.yml

@@ -34,6 +34,7 @@ jobs:
 
       - name: Build frontend into Host static assets
         run: |
+          cd frontend
           pnpm install --frozen-lockfile
           VERSION_DATE="$(TZ=Asia/Seoul date +%Y.%m.%d)"
           RELEASE_COUNT="$(git ls-remote --tags origin "refs/tags/v${VERSION_DATE}.*" | wc -l | tr -d ' ')"
@@ -45,9 +46,11 @@ jobs:
           grep -R -q 'app-version' dist
           grep -R -q 'UI contract 4.0' dist
           grep -R -q "${APP_VERSION}" dist
-          find ../src/KArtSell.Host/wwwroot -mindepth 1 -delete
-          cp -R dist/. ../src/KArtSell.Host/wwwroot/
-        working-directory: frontend
+          cd ..
+          rm -rf src/KArtSell.Host/wwwroot
+          mkdir -p src/KArtSell.Host/wwwroot
+          cp -r frontend/dist/* src/KArtSell.Host/wwwroot/
+          echo "✅ Frontend assets deployed to wwwroot"
 
       - run: dotnet restore KArtSell.sln