refactor(android)!: restructure to standard Capacitor plugin layout

Restructure Android project from nested module layout to standard
Capacitor plugin structure following community conventions.

Structure Changes:
- Move plugin code from android/plugin/ to android/src/main/java/
- Move test app from android/app/ to test-apps/android-test-app/app/
- Remove nested android/plugin module structure
- Remove nested android/app test app structure

Build Infrastructure:
- Add Gradle wrapper files (gradlew, gradlew.bat, gradle/wrapper/)
- Transform android/build.gradle from root project to library module
- Update android/settings.gradle for standalone plugin builds
- Add android/gradle.properties with AndroidX configuration
- Add android/consumer-rules.pro for ProGuard rules

Configuration Updates:
- Add prepare script to package.json for automatic builds on npm install
- Update package.json version to 1.0.1
- Update android/build.gradle to properly resolve Capacitor dependencies
- Update test-apps/android-test-app/settings.gradle with correct paths
- Remove android/variables.gradle (hardcode values in build.gradle)

Documentation:
- Update BUILDING.md with new structure and build process
- Update INTEGRATION_GUIDE.md to reflect standard structure
- Update README.md to remove path fix warnings
- Add test-apps/BUILD_PROCESS.md documenting test app build flows

Test App Configuration:
- Fix android-test-app to correctly reference plugin and Capacitor
- Remove capacitor-cordova-android-plugins dependency (not needed)
- Update capacitor.settings.gradle path verification in fix script

BREAKING CHANGE: Plugin now uses standard Capacitor Android structure.
Consuming apps must update their capacitor.settings.gradle to reference
android/ instead of android/plugin/. This is automatically handled by
Capacitor CLI for apps using standard plugin installation.

android/gradle.properties

@@ -1,22 +1,29 @@
-# Project-wide Gradle settings.
-
-# IDE (e.g. Android Studio) users:
-# Gradle settings configured through the IDE *will override*
-# any settings specified in this file.
-
-# For more details on how to configure your build environment visit
-# http://www.gradle.org/docs/current/userguide/build_environment.html
-
-# Specifies the JVM arguments used for the daemon process.
-# The setting is particularly useful for tweaking memory settings.
-org.gradle.jvmargs=-Xmx1536m
-
-# When configured, Gradle will run in incubating parallel mode.
-# This option should only be used with decoupled projects. More details, visit
-# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
-# org.gradle.parallel=true
+# Project-wide Gradle settings for Daily Notification Plugin
 
 # AndroidX package structure to make it clearer which packages are bundled with the
-# Android operating system, and which are packaged with your app's APK
-# https://developer.android.com/topic/libraries/support-library/androidx-rn
+# AndroidX library
 android.useAndroidX=true
+
+# Automatically convert third-party libraries to use AndroidX
+android.enableJetifier=true
+
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official
+
+# Enables namespacing of each library's R class so that its R class includes only the
+# resources declared in the library itself and none from the library's dependencies,
+# thereby reducing the size of the R class for that library
+android.nonTransitiveRClass=true
+
+# Enable Gradle build cache
+org.gradle.caching=true
+
+# Enable parallel builds
+org.gradle.parallel=true
+
+# Increase memory for Gradle daemon
+org.gradle.jvmargs=-Xmx2048m -XX:MaxMetaspaceSize=512m
+
+# Enable configuration cache
+org.gradle.configuration-cache=true
+