dsh-context-pack: DeepSeek Harness Context Pack Plugin

The DeepSeek Harness (DSH) plugin `dsh-context-pack` provides deterministic, privacy-aware repository context packaging. Through CLI commands or an API, it performs explicit, read-only scans of a repository, supports budgets based on file count and byte size, and excludes sensitive paths using a fail-closed policy. The plugin generates a SHA-256 hash of the context to verify content, does not modify source code at runtime, and makes no network requests. Users should note its positioning as a non-security tool, its current lack of full Git ignore compatibility, and the fact that v0.1 does not persist records.