[arniber21]

Closes #20

Summary

• document the policy path language, complete precedence behavior, and the three requested practical examples
• add a threat model that names retained disclosures, trust boundaries, keymap risk, and unsupported threats
• state the pseudonymization/anonymization boundary using current ICO guidance without making a legal-status guarantee
• link the threat model from the partner-facing README

Verification

• bun test — 186 passed
• bun run build
• git diff --check
• local documentation links and anonymity terminology audited

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