dsh-session-telecom: DeepSeek Harness Session Communication Plugin

`dsh-session-telecom` is a cross-session communication plugin for DeepSeek Harness (DSH), enabling inter-plugin collaboration via RPC. It supports session management, content reading, message sending, and data monitoring. After installation, the host must be restarted, and the desktop and web clients need to be installed separately. The plugin provides JSON-formatted action operations through the `session_telecom` tool, allowing users to read summaries, access raw data, and send messages to target sessions. When using the plugin, note the permission restrictions, stop-search rules, and potential costs caused by waking target sessions.