Route Grammar-v1 relations to exact Core propositions

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Summary

Continue Matrix SURF-008 / ledger PHIL-SURFACE-ELAB-001 with exact relation-operator routing from Grammar-v1 into Core propositions.

Contract

• all eight GrammarV1RelationOperator constructors preserve their source-selected semantic relation;
• > and >= canonicalize only by reversing operands into Core LessThan / LessEqual;
• in and disjoint remain native Member / Disjoint propositions;
• no relation is retried or reinterpreted as another category to obtain semantic acceptance.

Executable pressure

Phase1GrammarV1RelationElaborationMain.hs parses one claim for each of ==, !=, <=, >=, <, >, in, and disjoint, requires the exact parser operator sequence, then routes fixed semantic operands through the elaboration bridge and checks the exact Core proposition constructors and operand orientation.

This is the fourth bounded SURF-008 slice after #462, #464, and #466; full Grammar-v1 elaboration correspondence remains open.