fix(android): drop white-wrapping round PNG, single SVG-matched icon ring

Revert to a pure adaptive icon (the bare round PNG was getting legacy-wrapped
onto a white circle by the launcher). One ring only, in the foreground, using
the SVG's dark #000->#666 gradient on a plain dark tile.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Android/app/src/main/res/drawable/ic_launcher_background.xml

@@ -1,39 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Dark fill + the badge's metallic ring. The ring is scaled to ~0.68 so it
-     lands inside the adaptive-icon safe zone (the outer ~18dp is cropped by the
-     launcher) and reads at the edge of the visible circle. Brightened
-     grey->white so it's clearly visible on #0A0A0A. -->
+<!-- Plain dark tile. The badge (single SVG-matched ring + grid) is in the
+     foreground so there's exactly one ring. -->
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:aapt="http://schemas.android.com/aapt"
     android:width="108dp"
     android:height="108dp"
-    android:viewportWidth="752"
-    android:viewportHeight="752">
-
+    android:viewportWidth="108"
+    android:viewportHeight="108">
     <path
         android:fillColor="#0A0A0A"
-        android:pathData="M0,0h752v752H0z" />
-
-    <group
-        android:pivotX="376"
-        android:pivotY="376"
-        android:scaleX="0.68"
-        android:scaleY="0.68">
-        <path
-            android:fillColor="#0A0A0A"
-            android:strokeWidth="26"
-            android:pathData="M11.441,375.669a364.227,364.227 0 1,0 728.454,0a364.227,364.227 0 1,0 -728.454,0z">
-            <aapt:attr name="android:strokeColor">
-                <gradient
-                    android:type="linear"
-                    android:startX="751.337"
-                    android:startY="751.338"
-                    android:endX="0"
-                    android:endY="0">
-                    <item android:offset="0" android:color="#FF777777" />
-                    <item android:offset="1" android:color="#FFFFFFFF" />
-                </gradient>
-            </aapt:attr>
-        </path>
-    </group>
+        android:pathData="M0,0h108v108H0z" />
 </vector>

Android/app/src/main/res/drawable/ic_launcher_foreground.xml

@@ -12,8 +12,8 @@
     <group
         android:pivotX="376"
         android:pivotY="376"
-        android:scaleX="0.64"
-        android:scaleY="0.64">
+        android:scaleX="0.72"
+        android:scaleY="0.72">
 
         <!-- Ringed circle -->
         <path

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

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>