fix(cd): Add NEXT_PUBLIC_API_URL build-arg for Web build

Root cause: Frontend was compiled with default localhost:8000
instead of production URL https://awoooi.wooo.work

This caused all API calls to fail in production because the
browser tried to call localhost:8000 which doesn't exist.

Next.js NEXT_PUBLIC_* variables are baked in at BUILD TIME,
not runtime, so they must be passed via --build-arg.

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

.github/workflows/cd.yaml

@@ -142,6 +142,7 @@ jobs:
           echo "🎨 使用原生 Docker BuildKit 建構 Web..."
           docker build \
             --push \
+            --build-arg NEXT_PUBLIC_API_URL=https://awoooi.wooo.work \
             --tag ${{ env.REGISTRY }}/${{ env.IMAGE_PREFIX }}-web:${{ steps.tag.outputs.tag }} \
             --file apps/web/Dockerfile \
             .