feat: add revenue attribution resource

[christopherjnelson]

Summary

This PR implements Feature PR 2 from the feature roadmap: adding the Revenue Attribution resource (revenue) to the n8n-nodes-openanalytics node.

Operations Added

1. Get Summary (getSummary):
   • Queries GET /v1/read/revenue/summary
   • Supports site selection via dynamic search (getSites listSearch) or manual site ID
   • Required date range parameters from and to (ISO-8601 UTC format)
   • Optional parameters: timezone, compare (boolean), currency (3-letter currency filter)
2. Get Timeseries (getTimeseries):
   • Queries GET /v1/read/revenue/timeseries
   • Supports site selection via dynamic search (getSites listSearch) or manual site ID
   • Required date range parameters from and to (ISO-8601 UTC format)
   • Optional parameters: timezone, currency, grain (day, hour, month, week)

Verification

• 100% declarative routing (zero programmatic execution)
• Unit & contract tests: 31 tests passing across 5 test suites
• All 10 package scripts 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