dsh-instruction-audit: Minimal session trace for DeepSeek Harness instruction files

`dsh-instruction-audit` is a standalone community plugin for DeepSeek Harness (DSH) designed to address workspace instruction file auditing issues. When encountering nested workspace boundaries or instruction budget events, this tool accurately records which `AGENTS.md` or `CLAUDE.md` files actually entered the session without guesswork. Its core mechanism involves observing the persistent `agent-instructions` message source emitted by Harness and generating privacy-minimized receipts. Each receipt includes the session ID, event time, scope, display path, and a content summary, while not reading the original file, storing the instruction body, modifying the workspace, or requiring runtime dependencies. Receipts are stored in `$DS` by default.