Add app source for F-Droid release (v1.0.43)

Adds the full Android source tree with unit tests, fastlane store
metadata and the Gradle wrapper. The archive shipped without
gradle-wrapper.jar, so the official Gradle 9.7.1 wrapper jar is
included to make ./gradlew work from a fresh clone. .gitignore now
also excludes build output and keystores. README gains build
instructions and an updated structure tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015g6ECVSKcBG8CJPrqC3G5o

settings.gradle.kts

@@ -0,0 +1,17 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = "Matewave"
+include(":app")