test: warm cold dynamic imports before the timed cases

Under a full coverage run on every core, a test file's first cold import
(0.6-0.8 s alone) outran the 5 s case timeout and the half-done import
failed every later case in the file: the vitest lane went red in 2 of 5
runs with no defect. A beforeAll warm-up in the 4 files of that pattern;
5 of 5 full runs green after.

frontend/src/lib/accountPinnedStores.dom.test.ts

@@ -4,7 +4,7 @@
 // tab (bookmark, typed URL: no pin in sessionStorage) that is before BootGate pins the account, so they
 // read as nobody's; they must read again on the pin. The notification store used to keep its empty,
 // nobody's history, and the tab's first notice replaced the account's stored history with it.
-import { beforeEach, describe, expect, it, vi } from "vitest";
+import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 
 const entry = (id: number, message: string) => ({
   id,
@@ -24,6 +24,15 @@ const storedMessages = (account: number) =>
     }[]
   ).map((n) => n.message);
 
+// Warm the transform cache once (see verifyEntry.dom.test.tsx): the first cold import costs ~0.8 s
+// alone and outran the 5 s case timeout under a full coverage run. Transformed code outlives
+// vi.resetModules, so each case still gets fresh module instances, only faster.
+beforeAll(async () => {
+  await import("./notifications");
+  await import("./hints");
+  await import("./api/core");
+}, 60_000);
+
 beforeEach(() => {
   localStorage.clear();
   sessionStorage.clear();