fix: advertise NIP-13 (Proof of Work) in supportedNips

[Priyanshubhartistm]

Description

Adds 13 to the supportedNips array in package.json so the relay honestly advertises NIP-13 (Proof of Work) support.

Related Issue

Fixes #679

Motivation and Context

The relay already enforces NIP-13 PoW limits in canAcceptEvent() (src/handlers/event-message-handler.ts, via limits.event.eventId.minLeadingZeroBits and limits.event.pubkey.minLeadingZeroBits), and the README lists NIP-13 as supported. However package.json's supportedNips array did not include 13.
This array feeds supported_nips in the NIP-11 relay information document (src/handlers/request-handlers/root-request-handler.ts) and the startup log (src/app/app.ts), so clients inspecting the relay document had no way to know
PoW limits may be enforced, even though min_pow_difficulty was already present in the same document.

How Has This Been Tested?

• pnpm lint, pnpm check:deps, pnpm run build:check, pnpm run build,
  pnpm run verify:cli:build all pass.
• pnpm run test:unit (1393 passing) and pnpm run test:cli (73 passing) pass.
• pnpm run cover:unit completes successfully.
• pnpm run docker:test:integration run in full (99 scenarios): 97 passed

Screenshots (if appropriate):

N/A — data-only change to package.json.

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.
• I added a changeset, or this is docs-only and
• All new and existing tests passed.
• All new and existing tests passed.

[changeset-bot]

🦋 Changeset detected

Latest commit: 5b8f5b2

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

This PR includes changesets to release 1 package

Name	Type
nostream	Patch

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