[v6] Testing Infrastructure & Coverage #1500
Description
Scope: Establish Jest + coverage thresholds; implement unit & integration tests.
Acceptance Criteria:
- Jest configured (ts-jest) with coverage ≥80% lines/branches for core.
- Integration test simulates package->publish->share dry-run.
- Snapshot tests for task.json visibility rules.
Tasks: - Add jest config & scripts.
- Write service unit tests.
- Implement integration harness with mocks.
Labels: enhancement, help wanted