Enhance: Add hold piece control and theme customization options

- Introduced a new control for holding pieces with a swipe up gesture.
- Added multiple theme options with a Random Mode that changes themes automatically after clearing lines.
- Updated README to reflect new controls and visual features.
- Incremented version code and updated version name in build.gradle.
- Adjusted title and high score positioning based on screen orientation in TitleScreen.kt.
- Added "Enter Name" prompt in high score entry layout for better user experience.

app/build.gradle

@@ -11,8 +11,8 @@ android {
         applicationId "com.pixelmintdrop"
         minSdk 30
         targetSdk 35
-        versionCode 1
-        versionName "1.0"
+        versionCode 2
+        versionName "0.1"
         
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
     }