Minify frontend assets during image build

Dockerfile

@@ -1,3 +1,19 @@
+FROM node:22-bookworm-slim AS static-assets
+
+ARG ESBUILD_VERSION=0.25.8
+
+WORKDIR /build
+
+RUN npm install --global "esbuild@${ESBUILD_VERSION}" \
+  && test "$(esbuild --version)" = "${ESBUILD_VERSION}"
+
+COPY static/ /build/static/
+
+RUN cp -a static /out \
+  && esbuild static/app.js --minify --target=es2019 --charset=utf8 --legal-comments=none --outfile=/out/app.js \
+  && esbuild static/style.css --minify --outfile=/out/style.css \
+  && esbuild static/sw.js --minify --target=es2019 --charset=utf8 --legal-comments=none --outfile=/out/sw.js
+
 FROM python:3.11-slim
 
 WORKDIR /app
@@ -8,7 +24,7 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY app.py build_fulltext_db.py prepare_fulltext_index.py start.sh ./
 
-COPY static/ static/
+COPY --from=static-assets /out/ static/
 
 COPY data/ data/