feat: add expo-build-properties plugin to set minSdkVersion 26

Using expo-build-properties plugin for proper minSdk configuration.
Required for react-native-vad which needs Android O (API 26) or higher.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

android/.gitignore

@@ -0,0 +1,16 @@
+# OSX
+#
+.DS_Store
+
+# Android/IntelliJ
+#
+build/
+.idea
+.gradle
+local.properties
+*.iml
+*.hprof
+.cxx/
+
+# Bundle artifacts
+*.jsbundle