Greenfield RSS fixture

Read StakeholderDocuments/ and implement createStore in subscriptions.mjs. Run node --test --test-concurrency=1 contract.test.mjs. The starter fails intentionally; change implementation, not assertions.

Instructor checks in the curriculum checkout:

HANDS_ON_REFERENCE=1 node --test --test-concurrency=1 contract.test.mjs
HANDS_ON_REFERENCE=typescript node --test --test-concurrency=1 contract.test.mjs

References are excluded from learner preparation copies. The checks compare the same contract; they do not invoke Spec Kit, a model, or a network service.