feat(04-01): install new deps + scaffold API test harness with Wave-0 RED stubs

- Add react-router@7, @dnd-kit/core, @dnd-kit/sortable, fractional-indexing to PWA
- Add fractional-indexing to API (rank generation server-side)
- ioredis NOT added (in-memory EventEmitter per RESEARCH Plan 02 justification)
- Create apps/api/test/setup.ts with afterEach DB cleanup for list tables
- Wire test.setupFiles in apps/api/vitest.config.ts
- Add 4 Wave-0 RED stub test files (LIST-01/02/03/04, D-04, D-11, D-07)
- All stubs run as todo, not import-error

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

@@ -0,0 +1,19 @@
+/**
+ * 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)')
+})

apps/api/src/routes/lists.test.ts

@@ -0,0 +1,42 @@
+/**
+ * Wave-0 RED stubs for the lists API router.
+ *
+ * These stubs cover LIST-01 through LIST-04 behavior.
+ * Downstream plans (02/03/06) replace the `it.todo` entries with real assertions
+ * once the routes and DB are wired.
+ *
+ * Security focus: T-04-02 — scoped fan-out (private list events must NOT reach non-owner).
+ *
+ * Run: pnpm --filter @familysync/api test
+ */
+
+describe('GET /api/lists — LIST-01: returns only accessible lists', () => {
+  it.todo('returns empty array when user has no lists')
+  it.todo('returns lists owned by the current user')
+  it.todo('returns lists shared with the current user via list_shares')
+  it.todo('does NOT return private lists owned by another user')
+})
+
+describe('POST /api/lists — LIST-01: create list', () => {
+  it.todo('creates a list and inserts a list_shares row when isShared=true (D-01)')
+  it.todo('creates a private list with no list_shares row when isShared=false')
+  it.todo('rejects a name longer than 255 characters with 422')
+  it.todo('returns 401 when called without a session')
+})
+
+describe('PATCH /api/list-items/:id — LIST-02: per-field update', () => {
+  it.todo('updates only the checked field when patch body is { checked: true } (D-08)')
+  it.todo('updates only the text field when patch body is { text: "..." } (D-08)')
+  it.todo('rejects a patch body with more than one field with 422')
+  it.todo('returns 403 when caller does not own or share the parent list (T-04-02)')
+})
+
+describe('PATCH /api/list-items/:id rank — LIST-03: fractional reorder', () => {
+  it.todo('updates the rank field to the new fractional-indexing string')
+  it.todo('rejects an empty rank string with 422')
+})
+
+describe('SSE scoped fan-out — LIST-04 / T-04-02: private-list event isolation', () => {
+  it.todo('publishListEvent on a private list does NOT emit to a subscriber for a different list')
+  it.todo('publishListEvent on a shared list emits to all subscribers for that list')
+})