fix: fail closed on unusable Codex auth during sandbox auth merge

When reusing a Codex sandbox, the workspace-restore step now performs
an auth-merge check before adopting the sandbox's auth.json. The merge
fails closed when:

- host or sandbox Codex auth is unusable (missing token or account)
- the subscription payload shapes differ between host and sandbox
- subscription account identities do not match

Additional hardening: node absence on PATH during the embedded decision
script now exits non-zero instead of silently falling through. Co-change
comments link parseAuth (the embedded script) to hasUsableAuthPayload
(codex-home.ts) so a future auth-format change cannot silently diverge
between the two implementations.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

cli/src/client/command-label.ts

@@ -0,0 +1,4 @@
+export function buildCliCommandLabel(): string {
+  const args = process.argv.slice(2);
+  return args.length > 0 ? `paperclipai ${args.join(" ")}` : "paperclipai";
+}