feat: Flutter APK 编译成功 + Gradle 配置修复 + APK 下载部署 + 待优化清单

- 通过 qemu-user-static 实现 ARM64 主机编译 Android APK (51MB)
- 修复 Gradle: Aliyun 镜像 + PREFER_SETTINGS + JVM 内存 1536M
- 部署 APK 到 configs/downloads/, Web 下载接口已验证 (HTTP 200)
- 新增 Flutter TODO.md: 10项待优化 (P0/P1/P2 分级)
- 新增 pm_soul.md, 更新 routes.rs APK 下载路由

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

clients/flutter/lib/screens/playback_screen.dart

@@ -146,7 +146,7 @@ class _PlaybackScreenState extends State<PlaybackScreen> {
             return Padding(
               padding: const EdgeInsets.only(bottom: AppSpacing.sm),
               child: Card(
-                color: selected ? AppColors.primary.withOpacity(0.16) : null,
+                color: selected ? AppColors.primary.withValues(alpha: 0.16) : null,
                 child: ListTile(
                   onTap: provider.isLoading
                       ? null