feat(flutter): 强化开屏品牌标识展示

test/splash/splash_gate_test.dart

@@ -53,6 +53,23 @@ void main() {
     expect(find.byKey(const Key('splash-brand')), findsOneWidget);
     expect(find.byKey(const Key('splash-tagline')), findsOneWidget);
     expect(find.byKey(const Key('splash-loading')), findsOneWidget);
+    final mark = tester.widget<Image>(
+      find.byKey(const Key('splash-logo-mark')),
+    );
+    expect((mark.image as AssetImage).assetName, 'assets/icon/splash_mark.png');
+    expect(mark.width, 112);
+    expect(mark.height, 112);
+    final glow = tester.widget<Container>(
+      find.descendant(
+        of: find.byKey(const Key('splash-logo-glow')),
+        matching: find.byType(Container),
+      ),
+    );
+    final glowGradient = (glow.decoration as BoxDecoration).gradient;
+    expect(
+      (glowGradient as RadialGradient).colors.first,
+      const Color(0x40FF7A1A),
+    );
     expect(
       tester.widget<ColoredBox>(find.byKey(const Key('splash-screen'))).color,
       const Color(0xFF100C0A),