feat: ship verified platform upgrades with channel bundle releases

Package production dependencies per architecture for online and offline upgrades.
Validate dependencies and isolated backend startup before readiness, repair once
when permitted, and preserve service/data through failed preparation or rollback.

Publish release bundles with master images and expose an opt-in develop build
sharing the development index across Alpine and Debian images.

docker/Dockerfile.upgrade-bundle-armv6-glibc

@@ -0,0 +1,13 @@
+# An immutable digest of the CI-only ARM1176 validator, built in the same run.
+ARG BASE_IMAGE
+FROM ${BASE_IMAGE} AS bundle
+ARG BASE_IMAGE
+ENV QL_BUNDLE_BASE_IMAGE=${BASE_IMAGE}
+RUN ulimit -c 0; armv6-run /bin/bash -ec \
+    'node --jitless /ql/scripts/build-upgrade-bundle.cjs /ql /out; \
+     for archive in /out/*.tar.gz; do \
+       node /ql/shell/install-bundle.cjs --root /tmp/ql-bundle-offline-smoke --file "$archive" --install; \
+       rm -rf /tmp/ql-bundle-offline-smoke; \
+     done'
+FROM scratch
+COPY --from=bundle /armv6/out/ /