dsh-qq-agent-mail: Tencent QQ Agent Mail Integration under DeepSeek Harness

`dsh-qq-agent-mail` is a DeepSeek Harness plugin that wraps the official `@tencent-qqmail/agently-cli`, converting QQ Mail capabilities into native DSH features. It provides 14 tools covering authentication, reading and writing, attachment handling, and streaming monitoring, supports OAuth login, and offers a Web interface along with configuration options. By default, the plugin requires secondary confirmation for operations, enabling secure QQ Mail automation.