dist.sh builds versioned, signed artifacts for both apps from a git tag

(semver drives Android versionCode/versionName and package.json). The
build-image/ Dockerfile pins the same toolchain for a portable,
containerized Gitea Actions runner (build-image.sh builds and pushes
it) so releases don't depend on any one machine's local setup.
Pushing vX.Y.Z now builds and publishes a Gitea Release automatically.

build-image.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+# Builds and pushes the release build environment image (build-image/Dockerfile)
+# to the container registry. The Gitea Actions release workflow pulls this
+# image to run dist.sh. Bump build-image/VERSION whenever the Dockerfile
+# changes so the workflow can pin a stable tag.
+set -euo pipefail
+
+cd "$(dirname "${BASH_SOURCE[0]}")"
+ROOT="$(pwd)"
+
+fail() { echo "PREFLIGHT FAIL: $*" >&2; exit 1; }
+
+command -v docker >/dev/null 2>&1 \
+    || fail "docker not found in PATH"
+
+[ -f "$ROOT/registry.env" ] \
+    || fail "registry.env not found — copy registry.env.example to registry.env and fill in your cr.ladkau.de credentials"
+
+# shellcheck disable=SC1091
+source "$ROOT/registry.env"
+
+: "${REGISTRY:?registry.env must set REGISTRY}"
+: "${REGISTRY_IMAGE:?registry.env must set REGISTRY_IMAGE}"
+: "${REGISTRY_USER:?registry.env must set REGISTRY_USER}"
+: "${REGISTRY_PASSWORD:?registry.env must set REGISTRY_PASSWORD}"
+
+VERSION="$(<"$ROOT/build-image/VERSION")"
+[ -n "$VERSION" ] || fail "build-image/VERSION is empty"
+
+echo "== Logging in to $REGISTRY =="
+echo "$REGISTRY_PASSWORD" | docker login "$REGISTRY" -u "$REGISTRY_USER" --password-stdin
+
+echo "== Building $REGISTRY_IMAGE:$VERSION =="
+docker build \
+    -t "$REGISTRY_IMAGE:$VERSION" \
+    -t "$REGISTRY_IMAGE:latest" \
+    -f "$ROOT/build-image/Dockerfile" \
+    "$ROOT/build-image"
+
+echo "== Pushing $REGISTRY_IMAGE:$VERSION and :latest =="
+docker push "$REGISTRY_IMAGE:$VERSION"
+docker push "$REGISTRY_IMAGE:latest"
+
+echo "== Done =="
+echo "Image: $REGISTRY_IMAGE:$VERSION"