feat: add custom house launcher icon, themed splash screen, and F-Droid metadata

Replace default Flutter icon with white house on sage green (#7A9A6D) background.
Add native splash screen with themed colors (#F5F0E8 light, #2A2520 dark).
Include F-Droid metadata with screenshots for de-DE and en-US locales.
Add CHANGELOG.md tracking all releases from v1.0.0 to v1.1.3.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Theme applied to the Android Window while the process is starting when the OS's Dark Mode setting is off -->
+    <style name="LaunchTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:forceDarkAllowed">false</item>
+        <item name="android:windowFullscreen">false</item>
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:windowLayoutInDisplayCutoutMode">shortEdges</item>
+        <item name="android:windowSplashScreenBackground">#F5F0E8</item>
+        <item name="android:windowSplashScreenAnimatedIcon">@drawable/android12splash</item>
+        <item name="android:windowSplashScreenIconBackgroundColor">#7A9A6D</item>
+    </style>
+    <!-- Theme applied to the Android Window as soon as the process has started.
+         This theme determines the color of the Android Window while your
+         Flutter UI initializes, as well as behind your Flutter UI while its
+         running.
+         
+         This Theme is only used starting with V2 of Flutter's Android embedding. -->
+    <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
+        <item name="android:windowBackground">?android:colorBackground</item>
+    </style>
+</resources>