dsh-output-custody-proof: Non-Revealing Custody Proof for DSH Tool Outputs

`dsh-output-custody-proof` is a plugin in the DeepSeek Harness (DSH) ecosystem used to verify the custody and overflow retention of tool results without accessing their content. It does not read actual data and performs offline, deterministic validation based only on metadata, such as hashes, byte counts, and mappings, to ensure the integrity and consistency of results. The plugin provides MCP tools and command-line utilities that prove the correctness of results during the retention phase through strict metadata validation, while strictly protecting privacy by never touching the content payload. Installation requires DSH >= 0.1.2-alpha.4 and Node.js >= 22.