feat: break down billing totals

[alan-provable]

Closes #160

Summary

• Adds disabledStroops and unpricedRequests to the protocol billing total response.
• Preserves totalStroops as the aggregate for priced usage so existing dashboards keep their current meaning.
• Documents the breakdown fields in README.md.
• Adds focused regression tests for empty usage, all-enabled usage, disabled service usage, and unregistered service usage.

Validation

• npm run build
• npm run lint
• npm test
  • Passed after allowing local test listeners: 78 tests, 7 suites, 0 failures.
  • A sandboxed first run failed with listen EPERM: operation not permitted 0.0.0.0 because the test suite uses Supertest local HTTP listeners.
• git diff --check origin/main..HEAD

[mikewheeleer]

thanks for the effort @alan-provable! 🙏 issue #160 isn't assigned to you, and we merge from the assigned contributor to keep the campaign fair. please claim an open unassigned issue first, then open your PR. closing for now — hope to see it back 🙌

[mikewheeleer]

appreciate this — shipping it 🚀