Split the monolithic build-image.sh into three scripts: build-image.sh now only builds locally, run-image.sh

runs dist.sh inside that local image via a bind mount, andcupload-image.sh pushes the already-built image.
The Dockerfile also warms the Gradle dependency cache in a throwaway build stage, and pre-installs
the pinned CMake version, so `run-image.sh` doesn't re-download the same Maven dependencies on every run.

dist.sh now strips the -pre+meta suffix before writing package.json's version, since Pebble's build
tooling parses it strictly as X.Y.Z integers and was rejecting suffixed versions.

run-image.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# Runs dist.sh inside the local build-image container, mirroring what the
+# Gitea Actions release workflow does — useful for testing build-image
+# changes (or dist.sh/build_vice.sh/build_nibtools.sh changes) locally
+# before pushing anything to cr.ladkau.de.
+#
+# Usage: ./run-image.sh [VERSION]
+#   VERSION is passed through to dist.sh; omit it for dist.sh's own
+#   git-tag-based default (see dist.sh's header comment).
+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_IMAGE:?registry.env must set REGISTRY_IMAGE}"
+
+IMAGE_TAG="$(<"$ROOT/build-image/VERSION")"
+[ -n "$IMAGE_TAG" ] || fail "build-image/VERSION is empty"
+IMAGE="$REGISTRY_IMAGE:$IMAGE_TAG"
+
+docker image inspect "$IMAGE" >/dev/null 2>&1 \
+    || fail "$IMAGE not found locally — run ./build-image.sh first"
+
+VERSION="${1:-${VERSION:-}}"
+
+echo "== Running dist.sh inside $IMAGE =="
+docker run --rm \
+    -v "$ROOT:/workspace" \
+    -w /workspace \
+    -e VERSION="$VERSION" \
+    "$IMAGE" \
+    bash -c 'git config --global --add safe.directory /workspace && ./dist.sh'
+
+echo "== Done — artifacts in dist/ =="
+ls -la "$ROOT/dist"