chore(repo): Android-App als android/ ins Hauptrepo uebernehmen

Calendarr-Android wird mit vollstaendiger Historie als Unterverzeichnis
android/ eingebunden, damit Server, Web und die mobilen Apps in einem
Repo liegen.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

android/app/src/main/res/drawable/splash_icon.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- High-res logo inset so it sits comfortably inside the round splash mask. -->
+<inset xmlns:android="http://schemas.android.com/apk/res/android"
+    android:drawable="@drawable/ic_splash_logo"
+    android:inset="18%" />

android/app/src/main/res/drawable/splash_transparent.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!-- Invisible system-splash icon: the system splash is just black, so the
+     branded in-app splash (icon + name + copyright) is the only thing seen. -->
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <solid android:color="@android:color/transparent" />
+</shape>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+</adaptive-icon>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@color/ic_launcher_background"/>
+    <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+</adaptive-icon>

android/app/src/main/res/values-v31/themes.xml

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+<resources>
+    <style name="Theme.Calendarr" parent="Theme.Material3.DayNight.NoActionBar">
+        <item name="android:windowBackground">@color/splash_bg</item>
+        <item name="android:statusBarColor">@android:color/black</item>
+        <item name="android:navigationBarColor">@android:color/black</item>
+        <item name="android:windowLightStatusBar">false</item>
+    </style>
+</resources>

android/app/src/main/res/values/strings.xml

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+<resources>
+    <string name="app_name">Calendarr</string>
+</resources>

android/app/src/main/res/values/themes.xml

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+<resources>
+    <color name="splash_bg">#000000</color>
+    <color name="ic_launcher_background">#16703D</color>
+
+    <style name="Theme.Calendarr" parent="Theme.Material3.DayNight.NoActionBar">
+        <!-- Black window/system bars (matches the app background). -->
+        <item name="android:windowBackground">@color/splash_bg</item>
+        <item name="android:statusBarColor">@android:color/black</item>
+        <item name="android:navigationBarColor">@android:color/black</item>
+        <item name="android:windowLightStatusBar">false</item>
+    </style>
+
+    <!-- System splash (core-splashscreen): plain black with an invisible icon,
+         so the only branded screen the user sees is the in-app splash. -->
+    <style name="Theme.Calendarr.Starting" parent="Theme.SplashScreen">
+        <item name="windowSplashScreenBackground">@android:color/black</item>
+        <item name="windowSplashScreenAnimatedIcon">@drawable/splash_transparent</item>
+        <item name="postSplashScreenTheme">@style/Theme.Calendarr</item>
+    </style>
+</resources>