CVE-2026-63640: MagicMirror socket payload secret placeholder expansion can disclose SECRET_* environment variables

When hideConfigSecrets: true is enabled, MagicMirror redacts SECRET_* environment placeholders in the HTTP /config response, but the shared node-helper socket dispatcher expands **SECRET_NAME** placeholders in every inbound socket payload before passing it to module helpers. Any client that can connect to a loaded module namespace can send a placeholder such as **SECRET_API_KEY** and cause the server to substitute the real environment variable into the helper payload. Helpers that echo attacker-controlled payload fields, such as the default weather helper error path, can return the secret value to the socket client.