feat(app): launcher icon — brand logo 1024px + adaptive (blue #1A73E8 background)

flutter_launcher_icons 自动生成全尺寸 mipmap（48-192px + 自适应前景/背景）。
正式签名生产环境 APK 已打好。

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

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

@@ -0,0 +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>
+      <inset
+          android:drawable="@drawable/ic_launcher_foreground"
+          android:inset="16%" />
+  </foreground>
+</adaptive-icon>

apps/mobile/android/app/src/main/res/values/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#1A73E8</color>
+</resources>