feat: 커스텀 앱 아이콘 적용

- 파란색 그라데이션 배경의 미디어 재생 아이콘으로 변경
- flutter_launcher_icons 패키지를 사용하여 모든 플랫폼용 아이콘 자동 생성
- Android: adaptive icon 지원 추가 (배경색 #4A90E2)
- iOS: 모든 필수 크기의 아이콘 생성 (20x20 ~ 1024x1024)
- pubspec.yaml에 flutter_launcher_icons 설정 추가

🤖 Generated with [Claude Code](https://claude.ai/code)

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

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/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#4A90E2</color>
+</resources>

ios/Runner.xcodeproj/project.pbxproj

@@ -557,7 +557,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";
@@ -614,7 +614,7 @@
 			isa = XCBuildConfiguration;
 			buildSettings = {
 				ALWAYS_SEARCH_USER_PATHS = NO;
-				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = YES;
+				ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS = AppIcon;
 				CLANG_ANALYZER_NONNULL = YES;
 				CLANG_CXX_LANGUAGE_STANDARD = "gnu++0x";
 				CLANG_CXX_LIBRARY = "libc++";

pubspec.yaml

@@ -56,3 +56,15 @@ flutter:
   
   assets:
     - assets/data/
+    - assets/appicon/
+
+flutter_launcher_icons:
+  android: true
+  ios: true
+  image_path: "assets/appicon/appicon.png"
+  min_sdk_android: 21
+  # Android Adaptive Icon 설정
+  adaptive_icon_background: "#4A90E2"
+  adaptive_icon_foreground: "assets/appicon/appicon.png"
+  # iOS 설정
+  remove_alpha_ios: true