Opt-in RTK (Rust Token Killer) integration for the bash tool.
When enabled, commands are passed through rtk rewrite before execution;
commands RTK recognizes run as rtk <command> and return compressed
output, reducing token consumption. Commands without an RTK equivalent
(or any rtk failure) run unchanged.
Named per-peer trust tier for outbound A2A sends. limited (default)
keeps the historical behavior; sandboxed treats a send to this peer
as high-risk — on web/control chats it requires the explicit approval
flow before the message leaves. trusted is currently equivalent to
limited and reserved for future capability widening; tiers never
lower existing guardrails.