feat: add realtime token resource

[christopherjnelson]

Summary

This PR implements Feature PR 3: adding the Realtime resource (realtime) to the n8n-nodes-openanalytics community node package. With this addition, 100% of the Open Analytics API Read surface is natively supported.

Operations Added

• Get Token (getToken):
  • Issues POST /v1/read/realtime/token
  • Scoped to target site via x-oa-site header
  • Supports dynamic site selection via getSites listSearch locator or manual site ID
  • Returns short-lived streaming token and expiration for live presence and streaming widgets

Verification

• 100% declarative routing (zero programmatic runtime bloat)
• 32 tests passing across 5 test suites
• All 10 verification gates passed cleanly:
  • npm run format:check
  • npm run lint (0 errors / 0 warnings)
  • npm run typecheck
  • npm test
  • npm run build
  • npm run scan:source
  • npm run release:check
  • npm run package:check
  • npm run smoke:load
  • npm run smoke:install