Add configurable buttons, separate settings screens and backup activity

- Add ButtonConfigActivity for customizing main screen buttons with
  drag-and-drop reordering and individual size options (S/M/L)
- Move storage settings to separate StorageSettingsActivity
- Move signature setting to storage settings (relevant for WebDAV sync)
- Move data backup to separate BackupActivity with export/import
- Make "more" overflow button configurable in size
- Simplify SettingsActivity to 3 navigation buttons
- Add logbook rename/delete functionality
- Improve S/M/L button contrast with visible borders

app/build.gradle.kts

@@ -19,6 +19,10 @@ android {
     }
 
     buildTypes {
+        debug {
+            applicationIdSuffix = ".theo"
+            resValue("string", "app_name", "Theotracker")
+        }
         release {
             isMinifyEnabled = false
             proguardFiles(
@@ -52,6 +56,7 @@ dependencies {
     implementation(libs.androidx.appcompat)
     implementation(libs.androidx.recyclerview)
     implementation("com.github.thegrizzlylabs:sardine-android:v0.9")
+    implementation("com.google.android.flexbox:flexbox:3.0.0")
     implementation(libs.material)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)