Plans and implements comprehensive unit tests for the PABX monorepo — Angular frontend (Jest + jest-preset-angular, .spec.ts) and Node.js backend (Jest, apps/backend/__tests__/unit/). Runs interactively (3 phases with an approval checkpoint) when called by a user, or autonomously (no pause) when dispatched by implement-feature/evaluator. Also runs in correction mode to fix a specific failing test flagged by the evaluator. Enforces PABX rules (real component imports, manual service instantiation, localStorage/jQuery mock order, Promise.all() mock correctness, cleanup, English-only). Never modifies production code.
