Embedded Agent Toolkit 0.13.1

Adds a strict, host-only hardware test contract compiler and inspector. Contracts bind board selection, firmware and component-native workflow hashes, stage effects, dependencies, deadlines, assertions, and cleanup while remaining explicitly non-authorizing and non-executable. Includes JSON Schemas, an ESP32-S3 example, documentation, and release/install coverage. Also adds a release regression test that keeps the standalone Bootstrap version synchronized with both plugin manifests.