docs(readme): use English-localized screenshots in English README

The English README was reusing the Chinese-localized screenshots
(`home.png`, `home-dark.png`, `settings.png`, `browser.png`), which
left English readers staring at a UI they could not read. Ship a
parallel set of English screenshots under the `_en` suffix and point
`README.md` at them; `README.zh.md` / `README.jp.md` keep their own
assets untouched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -94,13 +94,13 @@ phones and tablets on the same Wi-Fi can open the web UI too.
 
 ## 📷 Screenshots
 
-![Home](./images/home.png)
+![Home](./images/home_en.png)
 
-![Home — dark mode](./images/home-dark.png)
+![Home — dark mode](./images/home-dark_en.png)
 
-![Settings](./images/settings.png)
+![Settings](./images/settings_en.png)
 
-![Resource extraction](./images/browser.png)
+![Resource extraction](./images/browser_en.png)
 
 ## 📥 Download