feat: complete advanced Sudoku workbench

playwright.config.ts

@@ -3,7 +3,10 @@ import { defineConfig, devices } from "@playwright/test";
 export default defineConfig({
   testDir: "./tests/browser",
   fullyParallel: false,
-  workers: 2,
+  // Run the two browser projects serially. Concurrent service-worker installs
+  // against the shared nested-path test server can make Firefox wait forever
+  // for the load event even though the application itself is healthy.
+  workers: 1,
   timeout: 120_000,
   expect: { timeout: 10_000 },
   reporter: [["list"]],