chore: update .gitignore and enhance backend and mobile app functionality

- Added mobile app build directories and configuration files to .gitignore for cleaner repository management.
- Improved error handling in diaryMemberController by requiring diaryDateId and memberId query parameters.
- Refactored DiaryMemberService to log tag IDs instead of raw values for better debugging.
- Enhanced TournamentParticipantsTab and TournamentTab components with improved touch-action properties for better user experience.
- Updated mobile app's gradle.properties and build.gradle.kts for compatibility with AGP 9.x and Kotlin 2.1.21, including new dependencies for Coil and UCrop.
- Refactored MainApplication to simplify initialization and improved MainActivity to handle dependencies more robustly.
- Updated various UI components in the mobile app to enhance layout and functionality, including MemberDetailScreen and MemberEditScreen.

mobile-app/gradle.properties

@@ -32,3 +32,13 @@ org.gradle.configuration-cache=true
 kotlin.code.style=official
 android.useAndroidX=true
 android.nonTransitiveRClass=true
+
+# Backend für die Standard-App-Installation.
+# Hinweis: In Android Studio unter Settings → Build Tools → Gradle können „Command-line options“
+# gesetzt sein (z. B. -PbackendBaseUrl=...) – die überschreiben u. U. diese Zeile.
+backendBaseUrl=https://tt-tagebuch.de
+
+# Temporary workaround for AGP 9.x + Kotlin Multiplatform plugin incompatibility.
+# (See AGP error message suggesting these flags.)
+android.builtInKotlin=false
+android.newDsl=false