fix(android): match icon ring to logo.svg gradient (#000->#666)

Revert the brightened grey->white ring back to the original logo.svg gradient
(black->#666, stroke 22.8834) on both the round PNG icon and the adaptive
foreground.

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

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

@@ -18,7 +18,7 @@
         <!-- Ringed circle -->
         <path
             android:fillColor="#0A0A0A"
-            android:strokeWidth="45"
+            android:strokeWidth="22.8834"
             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
@@ -27,8 +27,8 @@
                     android:startY="751.338"
                     android:endX="0"
                     android:endY="0">
-                    <item android:offset="0" android:color="#FF808080" />
-                    <item android:offset="1" android:color="#FFFFFFFF" />
+                    <item android:offset="0" android:color="#FF000000" />
+                    <item android:offset="1" android:color="#FF666666" />
                 </gradient>
             </aapt:attr>
         </path>