Write the parsed intent, the diagnostics and the descriptor as files the build leaves behind #128

Parent

#127

What to build

A run of the pipeline leaves behind everything the parity contract compares, as files, without any suite changing yet. The parsed Project Intent and Platform Intent, the diagnostics of a refused run, and the source metamodel's descriptor are written in the canonical JSON the oracles are committed in. The rendered tree is already written.

This is the expand half of the move: nothing is removed, and the suites keep calling Java, so a wrong output shape is caught here rather than after the suites depend on it.

Acceptance criteria

• A run over an accepted case writes its parsed intent as canonical JSON, byte-equal to the committed oracle.
• A run over a refused case writes its diagnostics as canonical JSON, the set of (code, JSON Pointer) pairs the contract fixes, order-independent.
• The build writes the metamodel descriptor from the same reflective walk that produces it today.
• Each file lands under the module's build output, is not committed, and is named so a case's file and its oracle are obviously a pair.
• ./mvnw -B -ntp verify is green from emf/, with the existing suites untouched.

Blocked by

• None (can start immediately).