Relocate e2e tests (#1989)

## Launch Checklist

Renames the e2e test and reduces changes as a preparation step from
playwright in the following PR:
- #1988

This is to keep as much history as possible.
<img width="1907" height="933" alt="image"
src="https://github.com/user-attachments/assets/b52075b3-eb3b-45dc-93dc-8c5e9cfd35dd"
/>

 - [x] Briefly describe the changes in this PR.

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

e2e/i18n.spec.ts

@@ -0,0 +1,37 @@
+import { MaputnikDriver } from "./maputnik-driver";
+
+const test = it;
+
+describe("i18n", () => {
+  const { beforeAndAfter, get, when, then } = new MaputnikDriver();
+  beforeAndAfter();
+
+  describe("language detector", () => {
+    test("English", () => {
+      const url = "?lng=en";
+      when.visit(url);
+      then(get.elementByTestId("maputnik-lang-select")).shouldHaveValue("en");
+    });
+
+    test("Japanese", () => {
+      const url = "?lng=ja";
+      when.visit(url);
+      then(get.elementByTestId("maputnik-lang-select")).shouldHaveValue("ja");
+    });
+  });
+
+  describe("language switcher", () => {
+    beforeEach(() => {
+      when.setStyle("layer");
+    });
+
+    test("the language switcher switches to Japanese", () => {
+      const selector = "maputnik-lang-select";
+      then(get.elementByTestId(selector)).shouldExist();
+      when.select(selector, "ja");
+      then(get.elementByTestId(selector)).shouldHaveValue("ja");
+
+      then(get.elementByTestId("nav:settings")).shouldHaveText("スタイル設定");
+    });
+  });
+});