cronos: build cronosd from GitHub release tarball; fix MIN_GAS and statesync RPC

GHCR image returns 403 on anonymous pulls — switch cometbft.Dockerfile to alpine +
public v1.7.8 tarball. init.sh sets minimum-gas-prices (5000000000000basecro) and
drops dead rpc-cronos.crypto.org statesync endpoint.

cronos/cometbft.Dockerfile

@@ -1,11 +1,21 @@
-ARG CRONOS_CRONOS_IMAGE
+# cronosd — public GitHub release tarball (ghcr.io/crypto-org-chain/cronos returns 403
+# on anonymous pulls). Mirror zero-gravity/zerog.Dockerfile: alpine base + tarball extract.
+ARG CRONOS_CRONOS_VERSION=v1.7.8
+
+FROM alpine:3.21
+
+RUN apk add --no-cache ca-certificates curl jq
+
 ARG CRONOS_CRONOS_VERSION
-FROM ${CRONOS_CRONOS_IMAGE}:${CRONOS_CRONOS_VERSION}
-# Layer the shared CometBFT bootstrap lib + the chain init.sh onto the upstream
-# cronos binary image (alpine-based, has sh+apk; runs nonroot by default — the compose
-# sets user: root so init.sh can apk-add curl and write the /root home).
-USER root
+RUN _ver="${CRONOS_CRONOS_VERSION#v}" && \
+    curl -fsSL "https://github.com/crypto-org-chain/cronos/releases/download/${CRONOS_CRONOS_VERSION}/cronos_${_ver}_Linux_x86_64.tar.gz" \
+      -o /tmp/cronos.tar.gz && \
+    tar -xzf /tmp/cronos.tar.gz -C /tmp && \
+    install -m 755 /tmp/bin/cronosd /usr/local/bin/cronosd && \
+    rm -rf /tmp/cronos.tar.gz /tmp/bin
+
 COPY ./scripts/cometbft-common.sh /usr/local/bin/cometbft-common.sh
 COPY ./scripts/init.sh            /usr/local/bin/init.sh
 RUN chmod +x /usr/local/bin/init.sh /usr/local/bin/cometbft-common.sh
+
 ENTRYPOINT ["init.sh"]