feat: Export events to JSON Lines

[Anshumancanrock]

Description

This PR adds npm run export [filename.jsonl] , a streaming CLI command that writes all stored events to a .jsonl file in NIP-01 format.

• Uses pg-query-stream to read rows via cursor (no full dataset in RAM)
• Each line is a JSON object with the 7 NIP-01 fields: id, pubkey, created_at, kind, tags, content, sig
• Skips soft-deleted events
• Logs progress every 10k rows
• Cleans up DB connection on exit

Related Issue

Closes #405

Motivation and Context

Relay operators currently have no built-in way to export events in a portable format. pg_dump works but is Postgres-specific and not useful for migrating between relay implementations or doing data analysis. This gives them a single command that outputs standard NIP-01 JSON Lines.

How Has This Been Tested?

• tsc --noEmit ( compiles clean )
• eslint ( no warnings )
• Ran npm run export against a local Postgres seeded with 3 million events
• Validated every line in the output is parseable JSON with exactly the 7 NIP-01 fields
• Tested custom filename: npm run export -- backup.jsonl
• Verified both runs produce identical output

Screenshots (if appropriate):

Types of changes

• Non-functional change (docs, style, minor refactor)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• All new and existing tests passed.

[Anshumancanrock]

Hi @cameri , Tested the exporter with the same events you sent :)