docs: language-matched README screenshots (EN + RU, v0.7.4 UI)

The single shared screenshot showed the Russian UI in both the English and
Russian README sections, and predated the v0.7.4 design. Regenerated two
fresh captures from the current build — English UI for the EN section,
Russian for the RU section.

Author: danscMax

README.md

@@ -53,7 +53,7 @@ Sidearm intercepts the key signals your mouse sends (F13--F24, etc.) and maps th
 
 ### Screenshot
 
-![Sidearm main view](docs/screenshots/main-view.png)
+![Sidearm main view](docs/screenshots/main-view-en.png)
 
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@@ -231,7 +231,7 @@ Sidearm перехватывает сигналы клавиш (F13--F24 и т.
 
 ### Скриншот
 
-![Sidearm главный вид](docs/screenshots/main-view.png)
+![Sidearm главный вид](docs/screenshots/main-view-ru.png)
 
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