[tests] migrate from jest to vitest (#3940)

This is a big change, but I think it's a good move, as `vitest` is much
more modern than `jest`.

I'm excited about the UI watch feature (run `npm run test:ui`), for
example - it's really helpful and saves time when debugging tests. I had
to adjust a few tests because they had time related issues, but
basically we are now testing the same things - even a bit better and
less flaky (I hope).

What do you think?

tests/utils/vitest-setup.js

@@ -0,0 +1,21 @@
+/**
+ * Vitest setup file for module aliasing
+ * This allows require("logger") to work in unit tests
+ */
+
+const Module = require("node:module");
+const path = require("node:path");
+
+// Store the original require
+const originalRequire = Module.prototype.require;
+
+// Override require to handle our custom aliases
+Module.prototype.require = function (id) {
+	// Handle "logger" alias
+	if (id === "logger") {
+		return originalRequire.call(this, path.resolve(__dirname, "../../js/logger.js"));
+	}
+
+	// Handle all other requires normally
+	return originalRequire.apply(this, arguments);
+};