scripts: unify Linux native builds and retain restore caches [CI]

Build musl and glibc for amd64 and arm64 through one native package path. Reuse musl outputs for OCI images and OpenWrt installers, and export binaries inside a rootless unshare session.

Restore the executable dependency graph into a shared persistent NuGet cache, build managed dependencies once, and run isolated native publishes in parallel.

Clean temporary outputs and expired image layers under store locks, retire inactive legacy stores after seven days, and retain two toolchain exports. Add regression coverage for staging, extraction, packaging and cleanup boundaries.

ci/publish-linux-agent.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# Publish one Linux package. Installation feeds reuse this build's binaries.
+set -euo pipefail
+rid="${1:?usage: publish-linux-agent.sh <rid> <binaries>}"; binaries="${2:?}"
+root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+source "$root/ci/version.sh"
+[[ -n "${GITEA_TOKEN:-}" ]] || { echo 'GITEA_TOKEN is required' >&2; exit 2; }
+if [[ -z "${CI_COMMIT_TAG:-}" ]]; then
+  bash "$root/ci/wait-for-checks.sh"
+  channel=dev
+else
+  channel=release
+fi
+work="$root/.release/linux-agent/$rid/packages"
+mkdir -p "$work"
+chmod 700 "$work"
+trap 'rm -f "$work/curl.conf"' EXIT
+bash "$root/ci/package-linux-agent.sh" "$rid" "$binaries" "$work"
+printf 'header = "Authorization: token %s"\n' "$GITEA_TOKEN" > "$work/curl.conf"
+chmod 600 "$work/curl.conf"
+base="${GITEA_BASE:-http://127.0.0.1:3100}"
+for file in "$work"/*.tar.gz "$work"/*.sha256; do
+  code="$(curl --silent --show-error --retry 3 --config "$work/curl.conf" --upload-file "$file" \
+    --output "$work/response" --write-out '%{http_code}' \
+    "${base%/}/api/packages/justme/generic/moshiro-node/$MOSHIRO_VERSION/$(basename "$file")")"
+  [[ "$code" == 2* || "$code" == 409 ]] || { echo "Linux package upload failed: HTTP $code" >&2; exit 1; }
+done
+# This is an installation adapter, not a separate native build or image extraction.
+# Preserve the installed OpenWrt updater's signed-feed contract.
+if [[ "$rid" == linux-musl-* && -n "${RELEASE_SIGNING_KEY:-}" && ( "$channel" == dev || "$MOSHIRO_VERSION" != *-* ) ]]; then
+  bash "$root/ci/publish-openwrt.sh" "$channel" "$rid" "$binaries"
+fi