Rewrite README for UI+Worker architecture, add guide links to tables

- Rewrite Quick Start, Architecture, Configuration, and Fleet Management
  sections to match actual UI+Worker split architecture
- Remove false monitor-only mode section (Docker socket always required via worker)
- Fix env vars table: add CASHPILOT_API_KEY, CASHPILOT_UI_URL, CASHPILOT_WORKER_NAME
- Add guide page links to every service in README tables
- Update MystNodes: note about beneficiary wallet matching cloud account
- Fix service counts (40+ total, 16+ Docker-deployable)

Author: GeiserX