Harden the hsm secret tool's encrypt flow and file validation

Harden the hsm secret tool's encrypt flow and file validation: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Our standalone HSM secret command-line utility ( tools/hsmtool ) lets operators encrypt and decrypt their node's hsm secret file with a password. Two…