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/README.md

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+# Mobile App (Native) – Kotlin Multiplatform
+
+Dieses Verzeichnis ist der Neustart der Mobile App als **wirklich native Android+iOS App** via **Kotlin Multiplatform (KMP)**.
+
+## Status
+- Der erste Versuch lag vorher in `mobile-app/` und wurde als Legacy gesichert.
+- Ein React-Native/Expo Restart-Versuch liegt in `mobile-app_legacy_rn_expo/` (nicht mehr der aktuelle Weg).
+
+## Auth (wichtig)
+Das Backend nutzt für die App/API **JWT Tokens**:
+- `POST /api/auth/login` → `{ token }`
+- Requests senden den Token als Header `authcode: <token>` (wie Webapp).
+
+## Plan
+Siehe `docs/MOBILE_APP_KMP_PLAN.md`.
+