feat(android): add temporary «Э» launcher icon (pending full rebrand)

Generate the Android launcher/adaptive icons + splashes with capacitor-assets from ui/assets/icon.png (the existing maskable brand mark upscaled 512→1024) as a placeholder until the mandatory single-vector icon rebrand recorded in ANDROID_PLAN.md. The adaptive icon insets the foreground 16.7% into the safe zone; the AndroidManifest is untouched (its icon refs already point at @mipmap).

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

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

@@ -1,5 +1,9 @@
 <?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"/>
+    <background>
+        <inset android:drawable="@mipmap/ic_launcher_background" android:inset="16.7%" />
+    </background>
+    <foreground>
+        <inset android:drawable="@mipmap/ic_launcher_foreground" android:inset="16.7%" />
+    </foreground>
 </adaptive-icon>