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/.gitignore

@@ -7,3 +7,14 @@
 # will have schema files for capabilities auto-completion
 /gen/schemas
 *log*
+
+# Android build artifacts
+/gen/android/app/build/
+/gen/android/build/
+/gen/android/.gradle/
+/gen/android/.tauri/
+/gen/android/local.properties
+/gen/android/key.properties
+/gen/android/keystore.properties
+/gen/android/tauri.settings.gradle
+/gen/android/app/src/main/jniLibs/