fix(docker): require single primary key before Docker apt GPG pin

Count `pub` records in gpg --with-colons output and abort unless exactly
one primary key is present, so we cannot verify only the first fingerprint
while apt imports every certificate from the armored file. Subkeys use
`sub`, so the official Docker signing key remains a single pub.

Fixes #74234

Made-with: Cursor

Dockerfile

@@ -238,9 +238,16 @@ RUN --mount=type=cache,id=openclaw-bookworm-apt-cache,target=/var/cache/apt,shar
         ca-certificates curl gnupg && \
       install -m 0755 -d /etc/apt/keyrings && \
       # Verify Docker apt signing key fingerprint before trusting it as a root key.
+      # Require exactly one primary key (`pub` in --with-colons; subkeys use `sub`) so we
+      # never pin the first fingerprint while apt trusts extra keys from the same file.
       # Update OPENCLAW_DOCKER_GPG_FINGERPRINT when Docker rotates release keys.
       curl -fsSL https://download.docker.com/linux/debian/gpg -o /tmp/docker.gpg.asc && \
       expected_fingerprint="$(printf '%s' "$OPENCLAW_DOCKER_GPG_FINGERPRINT" | tr '[:lower:]' '[:upper:]' | tr -d '[:space:]')" && \
+      docker_gpg_pub_count="$(gpg --batch --show-keys --with-colons /tmp/docker.gpg.asc | awk -F: '$1 == "pub" { c++ } END { print c+0 }')" && \
+      if [ "$docker_gpg_pub_count" != "1" ]; then \
+        echo "ERROR: Docker apt key must contain exactly one public key (found $docker_gpg_pub_count); refusing a multi-key file." >&2; \
+        exit 1; \
+      fi && \
       actual_fingerprint="$(gpg --batch --show-keys --with-colons /tmp/docker.gpg.asc | awk -F: '$1 == "fpr" { print toupper($10); exit }')" && \
       if [ -z "$actual_fingerprint" ] || [ "$actual_fingerprint" != "$expected_fingerprint" ]; then \
         echo "ERROR: Docker apt key fingerprint mismatch (expected $expected_fingerprint, got ${actual_fingerprint:-<empty>})" >&2; \