Model Platform Intent in Ecore, parse it, and check its cross-document references #86

Parent

#78

What to build

The Java side of #41. (Amended 2026-09-14 for the revised proposal, #102.) The Platform document becomes part of the source metamodel package, with Ecore references from a Project into it, because the proposal defines one source metamodel and the transformation resolves a Project against the platform data. The grammar parses the worked Platform document. Its referential invariants (an engine with no backup entry, a Durability Class with no policy, an audience no tier carries, a tier proxy naming no Application) are Complete OCL over the pair of documents.

Acceptance criteria

• The worked Platform document's Java canonical output equals its intent oracle, committed here if absent.
• Each referential invariant's refusal fixture yields its committed diagnostics set.
• The descriptor carries the Platform document's classes as part of the source metamodel, with cross-document references as references.

Blocked by

• Widen the Java Project Intent to every accepted example, and export its descriptor #84