Gmail_Email_Manager_v3

Production-ready Gmail REST API v1 email management skill (v3.0.0) implementing Four-Layer Integration Architect flow: (L1) Intent/Inputs, (L2) Orchestration/Guardrails, (L3) Gmail API Integration, (L4) Persistence/Observability. Supports profile lookup, label listing, message listing, message/thread retrieval, thread search, and steward-confirmed sending with RFC 2822 + base64url encoding, dedupe protection, thread integrity, and audit/testing.