feat(tcs): establish five-domain mother brain runtime

server-tools/code-channel-snapshot-admission/pre-receive

@@ -0,0 +1,12 @@
+#!/bin/sh
+set -eu
+
+validator="$(dirname "$0")/validate-public-snapshot-at-commit.js"
+while read -r old_value new_value ref_name; do
+  [ "$ref_name" = "refs/heads/main" ] || continue
+  [ "$new_value" = "0000000000000000000000000000000000000000" ] && {
+    echo "REPO-012 main deletion is forbidden" >&2
+    exit 1
+  }
+  node "$validator" --git-dir "$(git rev-parse --git-dir)" --commit "$new_value"
+done