make+app: add dockerized builder for app

We dockerize the app build and use that for both the docker build _AND_
the normal build to make sure the static content is fully reproducible
across different systems.

Makefile

@@ -164,13 +164,17 @@ app-build: yarn-install
 	@$(call print, "Building production app.")
 	cd app; yarn build
 
-release: app-build go-release
+docker-app-build:
+	@$(call print, "Building production app in docker.")
+	cd app; ./gen_app_docker.sh
+
+release: docker-app-build go-release
 
 go-release:
 	@$(call print, "Creating release of lightning-terminal.")
 	./scripts/release.sh build-release "$(VERSION_TAG)" "$(BUILD_SYSTEM)" "$(LND_RELEASE_TAGS)" "$(RELEASE_LDFLAGS)" "$(GO_VERSION)"
 
-docker-release: app-build
+docker-release: docker-app-build
 	@$(call print, "Building release helper docker image.")
 	if [ "$(tag)" = "" ]; then echo "Must specify tag=<commit_or_tag>!"; exit 1; fi
 

app/Dockerfile

@@ -0,0 +1,12 @@
+# Start with a NodeJS base image that also contains yarn.
+FROM node:22.8.0-bookworm@sha256:bd00c03095f7586432805dbf7989be10361d27987f93de904b1fc003949a4794 as nodejsbuilder
+
+RUN apt-get update && apt-get install -y git
+
+ENV HOME=/tmp
+
+RUN mkdir /build
+
+WORKDIR /build
+
+CMD ["/bin/bash", "-c", "chown $(id -u):$(id -g) /build && cd app && rm -rf node_modules && yarn cache clean && yarn install && yarn build"]

app/gen_app_docker.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -e
+
+# Directory of the script file, independent of where it's called from.
+DIR="$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)"
+
+echo "Building app compiler docker image..."
+docker build -q -t lit-app-builder .
+
+echo "Compiling app files..."
+docker run \
+  --rm \
+  --user $(id -u):$(id -g) \
+  -v "$DIR/../:/build" \
+  lit-app-builder