Context

PR #1870: policy_commands.rs wires /policy check with:

1. std::env::vars().collect() as policy context — real process env vars appear in the trace. On Telegram channel this could expose secrets.
2. Hardcoded TrustLevel::Trusted — the check command cannot simulate behavior for other trust levels.

Fix

• Use empty env map for /policy check context (it's a diagnostic tool, not a live evaluation)
• Accept optional --trust-level argument to /policy check