dsh-session-allow: Session-Level Permission Authorization Plugin

The `dsh-session-allow` plugin for DeepSeek Harness (DSH) overrides the approval panel to add an “Allow for this session” option, eliminating the need to manually confirm permissions during repeated testing. Once enabled, developers only need to authorize once, and the plugin will automatically approve subsequent requests within the current session. Authorization records are isolated by mode and can be revoked from the panel. The plugin is implemented by overriding the `conversation.composer` chain slot, with data stored locally and automatically cleared after a page refresh. Install command: `dsh plugin --profile web add https://github.com/AnakinCao/dsh-session-allow.git`.