Fix: remove custom fonts, add launcher icons

- Remove JetBrainsMono font assets (using google_fonts instead)
- Add adaptive icon and PNG fallbacks for launcher
- Build successful: app-release.apk (23.7MB)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

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

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M54,30 C38,30 26,42 26,58 C26,67 30,75 36,80 L36,85 C36,87 38,89 40,89 L48,89 C50,89 52,87 52,85 L52,82 L56,82 L56,85 C56,87 58,89 60,89 L68,89 C70,89 72,87 72,85 L72,80 C78,75 82,67 82,58 C82,42 70,30 54,30 Z M42,58 C39,58 37,56 37,53 C37,50 39,48 42,48 C45,48 47,50 47,53 C47,56 45,58 42,58 Z M66,58 C63,58 61,56 61,53 C61,50 63,48 66,48 C69,48 71,50 71,53 C71,56 69,58 66,58 Z"/>
+</vector>

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.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="@color/ic_launcher_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground"/>
+</adaptive-icon>

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

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#D97706</color>
+</resources>