feat(nip85): Web-of-Trust spam mitigation engine #720

Context & Problem

Current anti-spam measures (IP rate limiting, basic PoW) are insufficient against coordinated Sybil attacks. Operators need an intelligent way to filter out spammers based on decentralized cryptographic trust networks.

Proposed Solution

Build an active spam filter driven by NIP-85 assertions from configured Trust Providers.

Scope

• Assertion Ingestion: Will build a Trusted Assertion Service to ingest and cache kind: 30382 (User Assertions) from configured Trust Provider pubkeys.
• Trust Score Caching: Will maintain a high-performance Redis/PostgreSQL cache mapping pubkey -> trust_score.
• Spam Rejection Middleware: Will inject a validation step into the core event publishing pipeline to instantly reject events from negatively scored pubkeys (blocked: pubkey untrusted).

NIPs Involved: NIP-85