feat: add Android ARMv8 (aarch64) build support

- Initialize Tauri Android project structure (gen/android)
- Fix desktop_dir() unavailability on Android in file_explorer.rs and serial.rs
- Fix minimize/maximize/unmaximize unavailability on Android in window.rs
- Remove updater:default permission from default capabilities (not available on Android)
- Update .gitignore for Android build artifacts
- Successfully builds APK for aarch64-linux-android target

src-tauri/gen/android/app/.gitignore

@@ -0,0 +1,6 @@
+/src/main/**/generated
+/src/main/jniLibs/**/*.so
+/src/main/assets/tauri.conf.json
+/tauri.build.gradle.kts
+/proguard-tauri.pro
+/tauri.properties