dsh-terminal-context: Converting DSH Terminal Selections to File References

`dsh-terminal-context` is a client plugin for DeepSeek Harness designed to address the issue of long terminal log paste consuming context. It automatically converts selected terminal text into `@file` references, inserted via the “Add to context” button or the `Ctrl+L` shortcut, with automatic formatting cleanup. Captured files are stored in the `.dsh/term-captures/` directory. It supports a fallback mode and effectively keeps the conversation flow clean.