Goldens: three variants at 1x density (sv_light, sv_dark, en_light; D-098)

Drop the en_dark variant from every screenshot helper and render every
golden at mdpi (Robolectric qualifier w411dp-h<height>dp-mdpi instead of
xhdpi/xxhdpi), so a 411 x 891 dp screen is 411 x 891 px. All goldens
deleted and re-recorded; 1143 -> 865 PNGs. README describes the layout.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TQd3pEP9UeN2uifbHknQ7B

android/app/src/test/kotlin/se/hagstedt/kvitt/KvittEmptyScreenScreenshotTest.kt

@@ -19,7 +19,7 @@ import se.hagstedt.kvitt.design.KvittTheme
  */
 @RunWith(RobolectricTestRunner::class)
 @GraphicsMode(GraphicsMode.Mode.NATIVE)
-@Config(sdk = [36], qualifiers = "w411dp-h891dp-xxhdpi", application = Application::class)
+@Config(sdk = [36], qualifiers = "w411dp-h891dp-mdpi", application = Application::class)
 class KvittEmptyScreenScreenshotTest {
     @get:Rule
     val compose = createComposeRule()