dsh-approval-first

Approval-first edit/write for DeepSeek Harness: shadow tools ask the user BEFORE a mutation the standing sandbox policy would deny, so the model never has to repeat a tool call with sandbox_permissions. In-policy writes stay silent, out-of-policy targets get an approval card on the first call. Registration follows the session's current standing mode live; a boot-time drift tripwire refuses to activate when the shipped edit/write definitions no longer match the frozen copies.