Trust: improve ERC-8004 and trust-policy documentation and examples

[Abiorh001]

Summary

Trust is a key OmniClaw differentiator and needs stronger developer-facing guidance.

Problem

Developers need clearer documentation for:

• what trust checks do
• how allow / hold / block behavior works
• when to use check_trust
• how ERC-8004-style identity fits into payment decisions

Acceptance criteria

• trust explainer is added or improved
• examples show trust-enabled simulate/pay flows
• policy presets are documented clearly
• README and docs link to the trust documentation