PutSecureSettingTool

settings put secure <key> <value> — write a Settings.Secure value, which most apps cannot do without privileged shell access. Idempotent. Delegates to putSetting; treated as failure on non-zero exit or non-empty stderr.

Privilege: requires a working ShellBackend.

Params: key (required), value (required).

On success the result map carries success (true), namespace ("secure"), key, and value.