refactor: 移除 LiteLLM proxy 架构，后端直连 Provider API

- 移除 backend/scripts/build_litellm_proxy_config.py
- 简化 LiteLLMService，移除 run_completion_with_cost 方法
- AgentScopeRunner 改为从 LlmFactory 获取 api_base 和 api_key
- 部署配置移除 litellm/litellm-config-job 服务
- Flutter 新增 AuthBootScreen 引导页
- Android 添加通知权限 (POST_NOTIFICATIONS, RECEIVE_BOOT_COMPLETED, SCHEDULE_EXACT_ALARM)
- 优化 LocalNotificationService 调度失败 fallback
- 更新 manifest.json (version 3)

apps/lib/features/auth/ui/screens/auth_boot_screen.dart

@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+
+import '../../../../core/theme/design_tokens.dart';
+import '../../../../shared/widgets/app_loading_indicator.dart';
+
+class AuthBootScreen extends StatelessWidget {
+  const AuthBootScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Scaffold(
+      backgroundColor: AppColors.authBackgroundTop,
+      body: SafeArea(
+        child: Center(
+          child: AppLoadingIndicator(
+            variant: AppLoadingVariant.surface,
+            size: 28,
+            strokeWidth: 2.5,
+            color: AppColors.authPrimaryButton,
+            trackColor: AppColors.authPrimaryButtonDisabled,
+          ),
+        ),
+      ),
+    );
+  }
+}