dsh-change-window-proof: Offline Deterministic Change-Window Evidence

`dsh-change-window-proof` is an offline, deterministic evidence-generation plugin for verifying that change settlement occurs strictly within declared maintenance windows. It supports use via DSH bundles, an MCP stdio server, a JavaScript API, and a CLI. The plugin provides maintenance-window validation, duration and truncation checks, binding validation, and SHA-256 chain validation, and generates content-hash-based verifiable reports. It does not perform change operations or query live infrastructure; instead, it audits change logs to ensure that changes strictly comply with time limits and policy requirements, serving as a critical component of the change-management evidence stack.