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/pubspec.yaml

@@ -40,6 +40,14 @@ dependencies:
   gal: ^2.3.3
   fluwx: ^6.0.2
 
+
+flutter_launcher_icons:
+  android: true
+  ios: false
+  image_path: "assets/brand/app-icon.png"
+  adaptive_icon_background: "#1A73E8"
+  adaptive_icon_foreground: "assets/brand/app-icon.png"
+
 dev_dependencies:
   flutter_test:
     sdk: flutter
@@ -49,6 +57,7 @@ dev_dependencies:
   flutter_lints: ^6.0.0
   build_runner: ^2.15.1
   drift_dev: ^2.35.0
+  flutter_launcher_icons: ^0.14.0
 
 flutter:
   # l10n 代码生成（arb 见 lib/l10n/，配置见 l10n.yaml）