refactor: 大规模模块拆分与代码精简，新增 ai-pipeline/data-contracts 独立 crate

- 新增 aether-ai-pipeline 和 aether-data-contracts crate，将 pipeline 逻辑与数据契约从 gateway 中解耦
- 重构 admin handlers：拆分单体模块为 auth/billing/endpoint/features/model/observability/provider/system 等独立子模块
- 合并 chat/cli 重复代码路径：精简 conversion、finalize、planner 中的 sync/chat/cli 分支
- 重构 scheduler/executor/data 层，引入 facade 模式降低模块间耦合
- 移除冗余的 intent 模块，将 plan_fallback/policy/stream_path/sync_path 迁移至 executor
- 前端适配：调整 admin API 调用和 provider 模型测试对话框

apps/aether-gateway/src/maintenance/runtime/provider_checkin.rs

@@ -1,12 +1,12 @@
 use std::collections::HashMap;
 
-use aether_data::repository::provider_catalog::{
+use aether_data_contracts::repository::provider_catalog::{
     StoredProviderCatalogEndpoint, StoredProviderCatalogProvider,
 };
 use futures_util::stream::{self, StreamExt};
 use tracing::{debug, warn};
 
-use crate::handlers::admin::provider_ops::admin_provider_ops_local_action_response;
+use crate::handlers::admin::provider::ops::admin_provider_ops_local_action_response;
 use crate::{AppState, GatewayError};
 
 use super::{system_config_bool, PROVIDER_CHECKIN_CONCURRENCY};