refactor(04-01): move API list test stubs into tests/ mirror dir to match convention

The two Wave-0 RED stubs (lists.test.ts, listEmitter.test.ts) were co-located in
src/ but all existing API tests live in apps/api/tests/. Move them to tests/routes/
and tests/lib/, add explicit vitest imports to match the tests/ convention, and
update path references in downstream plans 04-02..04-06. PWA tests keep co-location
(that IS the PWA convention).

apps/api/src/lib/listEmitter.test.ts

@@ -1,19 +0,0 @@
-/**
- * Wave-0 RED stubs for listEmitter (in-memory EventEmitter fan-out).
- *
- * Covers D-04: SSE fan-out MUST be scoped to who can see a list.
- * These are pure-unit tests — no DB or HTTP server needed.
- *
- * Downstream plans implement the actual listEmitter.ts module that these stubs test.
- *
- * Run: pnpm --filter @familysync/api test
- */
-
-describe('listEmitter — scoped fan-out correctness (D-04)', () => {
-  it.todo('publishListEvent emits only to subscribers for the matching listId')
-  it.todo('publishListEvent does NOT emit to subscribers for a different listId')
-  it.todo('subscribeListEvents returns an unsubscribe function that stops future events')
-  it.todo('unsubscribed handler is not called after unsubscribe()')
-  it.todo('multiple subscribers for the same listId all receive the event')
-  it.todo('emitter handles 100+ concurrent subscribers without error (D-18 scale check)')
-})