feat: Add NIP-50 full-text search support

[Anshumancanrock]

Adds search filter support to REQ messages using PostgreSQL full-text search. Disabled by default.

["REQ", "sub1", {"search": "bitcoin lightning", "kinds": [1], "limit": 20}]

What this does

• Accepts search in REQ filters, validated via Zod schema
• Queries events using to_tsvector/plainto_tsquery with a GIN index
• Ranks results by ts_rank instead of created_at
• Matches live subscriptions in-memory (case-insensitive term matching)
• Strips search from filters when disabled (per spec: silently ignore)
• Advertises search_supported in the NIP-11 document
• Migration adds the GIN index via CREATE INDEX CONCURRENTLY

Configuration

nip50:
  enabled: false
  language: simple       # or 'english', 'spanish', etc.
  maxQueryLength: 256

Tests

• Unit: schema validation, in-memory matching, NIP-11, repository queries
• Integration: search match, no-match, combined with kind filter

[changeset-bot]

🦋 Changeset detected

Latest commit: ea52a30

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
nostream	Major

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[coveralls]

coverage: 64.212% (+0.2%) from 64.015% — Anshumancanrock:feat/nip-50-search into cameri:main