feat: complete MDX migration, stabilize environment & verify via E2E tests

Former-commit-id: ec3e64156a2e182535cbdcf0d975cd54603a517d

i18n/request.ts

@@ -14,11 +14,9 @@ export default getRequestConfig(async ({ requestLocale }) => {
     // console.debug(`[i18n] Fallback to "de" for locale: "${rawLocale}"`);
   }
 
-  console.log(`[i18n] Resolved locale: ${locale}`);
   let messages;
   try {
     messages = (await import(`../messages/${locale}.json`)).default;
-    console.log(`[i18n] Loaded messages for ${locale}`);
   } catch (error) {
     console.error(`[i18n] Error loading messages for ${locale}:`, error);
     messages = {};