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/trigger_screen.dart

@@ -133,7 +133,7 @@ class _TriggerScreenState extends State<TriggerScreen> {
                   Text('场景切换', style: Theme.of(context).textTheme.titleMedium),
                   const SizedBox(height: AppSpacing.md),
                   DropdownButtonFormField<String>(
-                    value: provider.sceneOptions.contains(_selectedScene) ? _selectedScene : null,
+                    initialValue: provider.sceneOptions.contains(_selectedScene) ? _selectedScene : null,
                     items: provider.sceneOptions
                         .map(
                           (scene) => DropdownMenuItem<String>(