Fix e2e tests: Set English language before navigation

- Add context.addInitScript in beforeEach hooks to set English locale before page navigation
- Remove debugging code from useLanguage hook
- Remove unused setup file imports
- Fix exchange test to check for English text correctly
- All frontend tests passing

frontend/playwright.config.ts

@@ -20,21 +20,5 @@ export default defineConfig({
     // Reduce screenshot/recording overhead
     screenshot: "only-on-failure",
     trace: "retain-on-failure",
-    // Set language to English for all e2e tests via localStorage
-    // E2E tests should only test in English according to requirements
-    storageState: {
-      cookies: [],
-      origins: [
-        {
-          origin: "http://localhost:3000",
-          localStorage: [
-            {
-              name: "arbret-locale",
-              value: "en",
-            },
-          ],
-        },
-      ],
-    },
   },
 });