chore: 添加 .gitignore 文件

android-app/.gitignore

@@ -0,0 +1,17 @@
+*.iml
+.gradle
+/local.properties
+/.idea/caches
+/.idea/libraries
+/.idea/modules.xml
+/.idea/workspace.xml
+/.idea/navEditor.xml
+/.idea/assetWizardSettings.xml
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+/app/src/androidTest/java/com/uiui/os/
+/app/src/test/java/com/uiui/os/
+/.idea/

android-app/app/.gitignore

@@ -0,0 +1 @@
+/build