chore: get Android project building (toolchain, deps, manifest, launcher icon)

- Fix dependency versions (Retrofit 2.11, OkHttp 4.12, Compose BOM)
- Add Material Components for the app theme
- Add --add-exports/--add-opens for kapt on JDK 21
- Remove deprecated manifest package attr; add INTERNET permission
- Add adaptive launcher icon

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,46 @@
+# Built application files
+*.apk
+*.aar
+*.ap_
+*.aab
+
+# Files for the ART/Dalvik VM
+*.dex
+
+# Java class files
+*.class
+
+# Generated files
+bin/
+gen/
+out/
+release/
+
+# Gradle files
+.gradle/
+build/
+
+# Local configuration file (sdk path, etc.)
+local.properties
+
+# Log files
+*.log
+
+# Android Studio / IntelliJ
+*.iml
+.idea/
+*.ipr
+*.iws
+captures/
+.externalNativeBuild/
+.cxx/
+
+# Keystore files
+*.jks
+*.keystore
+
+# macOS
+.DS_Store
+
+# Kotlin
+.kotlin/