multi-tenant 3

A DSH-native multi-tenant plugin with trusted Principal contexts, Principal-scoped Agent resources, durable local ownership, and Agent-scoped MCP capabilities.

DSH 多租户账户与授权插件：PostgreSQL 存储 + admin 管理 API + 每账户独立工作目录（独立插件，不改 DSH 核心）

Single-process multi-user workspace view partitioning for DeepSeek Harness: JWT-in-cookie login wall, per-user workspace/session filtering, and admin user management.