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).

.planning/phases/04-shared-lists-live-sync/04-02-PLAN.md

@@ -6,7 +6,7 @@ wave: 2
 depends_on: ["04-01"]
 files_modified:
   - apps/api/src/lib/listEmitter.ts
-  - apps/api/src/lib/listEmitter.test.ts
+  - apps/api/tests/lib/listEmitter.test.ts
   - apps/api/src/lib/listAccess.ts
   - apps/api/src/lib/listAccess.test.ts
 autonomous: true
@@ -26,7 +26,7 @@ must_haves:
     - path: "apps/api/src/lib/listAccess.ts"
       provides: "getAccessibleListIds(userId) access-scope query"
       exports: ["getAccessibleListIds"]
-    - path: "apps/api/src/lib/listEmitter.test.ts"
+    - path: "apps/api/tests/lib/listEmitter.test.ts"
       provides: "scoped fan-out correctness tests (D-04)"
       contains: "describe"
   key_links:
@@ -65,11 +65,11 @@ Output: `publishListEvent`/`subscribeListEvents` (in-memory EventEmitter singlet
 <feature>
   <name>Scoped in-memory list event fan-out + access-scope query (D-04)</name>
   <files>
-    apps/api/src/lib/listEmitter.ts, apps/api/src/lib/listEmitter.test.ts,
+    apps/api/src/lib/listEmitter.ts, apps/api/tests/lib/listEmitter.test.ts,
     apps/api/src/lib/listAccess.ts, apps/api/src/lib/listAccess.test.ts
   </files>
   <read_first>
-    - apps/api/src/lib/listEmitter.test.ts (RED stub from Plan 01 — convert to real assertions)
+    - apps/api/tests/lib/listEmitter.test.ts (RED stub from Plan 01 — convert to real assertions)
     - apps/api/src/db/schema.ts (lists, listShares tables created in Plan 01)
     - apps/api/src/routes/events.ts lines 1-110 (db query + drizzle and/or/eq conventions)
     - .planning/phases/04-shared-lists-live-sync/04-RESEARCH.md Finding 1 + Finding 3 (verbatim patterns)
@@ -116,7 +116,7 @@ Output: `publishListEvent`/`subscribeListEvents` (in-memory EventEmitter singlet
 </threat_model>
 
 <verification>
-<automated>pnpm --filter @familysync/api exec vitest run src/lib/listEmitter.test.ts src/lib/listAccess.test.ts</automated>
+<automated>pnpm --filter @familysync/api exec vitest run tests/lib/listEmitter.test.ts src/lib/listAccess.test.ts</automated>
 - Test 2 (cross-list isolation) and Test 7 (private list excluded) MUST be present and green.
 </verification>
 
@@ -131,7 +131,7 @@ Output: `publishListEvent`/`subscribeListEvents` (in-memory EventEmitter singlet
 **Symbols/files this plan creates (exclude from drift verification):**
 - `apps/api/src/lib/listEmitter.ts` exporting `publishListEvent(listId, event)`, `subscribeListEvents(listId, handler): () => void`, type `ListEvent`
 - `apps/api/src/lib/listAccess.ts` exporting `getAccessibleListIds(userId): Promise<number[]>`
-- Tests: `apps/api/src/lib/listEmitter.test.ts`, `apps/api/src/lib/listAccess.test.ts`
+- Tests: `apps/api/tests/lib/listEmitter.test.ts`, `apps/api/src/lib/listAccess.test.ts`
 </artifacts_produced>
 
 <output>