dsh-safe-tui: DeepSeek Harness Safety Mode and Terminal Repair

`dsh-safe-tui` is a safe mode/repair mode TUI plugin for DeepSeek Harness (DSH). By using environment isolation (no user plugins or Web UI are loaded) and restricted interactions, it is designed to solve issues where the main interface cannot be opened due to plugin conflicts or corruption. The plugin supports terminal commands and internal TUI commands, and includes session management, file repair, and Web console features. Since v0.6.0, it supports same-session handoff, allowing users to switch seamlessly from the Web interface to the safe terminal to continue a conversation. The plugin is currently in development, so users assume any risks after installation.