Claude-Code-Styled TUI for DeepSeek Harness

Key features

• The runtime probe appends a real event and checks seq, eventAt(), snapshot readback, and persistence flush.
• Structured questions use DSH's Agent-scoped user-questions/request waterfall.
• Model/provider configuration uses the current settings API.
• PTC mode now uses upstream's ptc value.
• The launcher and bundle still accept DSH_TOOLS_MODE=code as an alias.