Make emf/ navigable and its parity tier independent

[ExtraToast]

Parent

#78

What to build

emf/ reads as one flat list of six Eclipse bundles, and nothing in the listing says which of them a course examiner opens and which exist only for this repository's own evidence. The parity suite is the sharpest case: it reaches past the pipeline's interface into Pipeline, Parsed, Diagnostic and Descriptor, which is why parity/pom.xml is eclipse-plugin packaging while emf/docs/architecture.md says a module needing no p2 bundle stays a plain jar. That drift is live.

This epic closes it in the order the two decisions take: the parity suite moves onto the pipeline's file interface and becomes a plain jar, then the tree splits into bundles/ for what Tycho builds and Eclipse imports and tests/ for what only Maven runs, and the second tier is ported to Kotlin, the estate's JVM language.

Decided in 0120 and 0121, recorded in #126. Neither is implemented there: emf/docs/architecture.md still describes the tree as it is, with each decision beside it as a "proposed, not landed" note. This epic is what removes those notes.

Acceptance criteria

• tests/parity builds as a plain jar, holds no EMF type, and resolves nothing from the target platform.
• EMF-010 and EMF-011 still fail on a fixture that breaks them, rather than passing on an empty class import.
• bundles/ holds the five graded modules and tests/ the parity tier; ./mvnw -B -ntp verify is green from emf/.
• emf/README.md answers "where does this artefact live, and which task grades it" in one table.
• Both "proposed, not landed" notes are gone from emf/docs/architecture.md, because the tree matches what it says.

Blocked by

• None (can start immediately).