dsh-session-surgeon: Fix unresolvable DSH sessions and enable new sessions to reference old sessions

`dsh-session-surgeon` is an MIT-licensed DSH plugin designed to address issues where DeepSeek Harness sessions fail to load and context inheritance problems occur. It provides session repair, inspection, export, and ID copying functionalities and is compatible with `@deepseek-ai/dsh@0.1.0-rc.6`. Core features include providing entry points for "Copy Session ID", "Inspect", and "Dry-Run Repair" in the DSH session menu and sidebar, supporting browsing, repairing, previewing, and exporting JSONL. The plugin is capable of fixing errors such as sequence gaps, torn zstd frames, lone surrogates, and missing message IDs, while inspection only issues warnings without fabricating results.