test(canopy-rules): auto-generate JSON-schema from JDM ruleset inputs

cargo xtask rules check could emit a JSON-schema per ruleset describing the required / optional input fields (name, type, default). Happy-path test fixtures would then be validated against the generated schema, catching drift between the ruleset's declared inputs and the test data.

Extracted from jdm-ruleset-happy-path-tests.adoc § Potential Improvements.