fix(weather): show correct wind speed and unit for imperial units

When OPENWEATHER_UNITS=imperial, OpenWeatherMap returns wind speed in
mph directly — the server was incorrectly multiplying by 3.6 (m/s→km/h)
on top of that. All locale strings also hardcoded the unit label instead
of using a {{windUnit}} placeholder, so the label always read km/h.

Resolves #79

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/locales/ru.json

@@ -65,7 +65,7 @@
     "weatherRefresh": "Обновить погоду",
     "weatherRefreshTitle": "Обновить",
     "weatherUpdated": "Погода обновлена",
-    "weatherFeelsLike": "Ощущается как {{temp}}° · {{humidity}}% · Ветер {{wind}} км/ч",
+    "weatherFeelsLike": "Ощущается как {{temp}}° · {{humidity}}% · Ветер {{wind}} {{windUnit}}",
     "fabTaskLabel": "Добавить задачу",
     "fabCalendarLabel": "Добавить событие",
     "fabShoppingLabel": "Добавить покупку",