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.

dist.sh

@@ -87,7 +87,11 @@ sed -i \
     -e "s/versionCode = [0-9]\+/versionCode = $VERSION_CODE/" \
     -e "s/versionName = \"[^\"]*\"/versionName = \"$VERSION\"/" \
     "$GRADLE_KTS"
-sed -i -e "s/\"version\": \"[^\"]*\"/\"version\": \"$VERSION\"/" "$WATCH_PKG_JSON"
+# Pebble's own build tooling parses package.json's version strictly as
+# X.Y.Z integers — it rejects the -pre+meta suffix dist.sh otherwise allows
+# (including the default "0.0.0-dev+<sha>" placeholder), so strip it here.
+PEBBLE_VERSION="${BASH_REMATCH[1]}.${BASH_REMATCH[2]}.${BASH_REMATCH[3]}"
+sed -i -e "s/\"version\": \"[^\"]*\"/\"version\": \"$PEBBLE_VERSION\"/" "$WATCH_PKG_JSON"
 
 mkdir -p "$DIST"