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/tests/control/admin/adaptive.rs

@@ -1,7 +1,8 @@
 use std::sync::{Arc, Mutex};
 
-use aether_data::repository::provider_catalog::{
-    InMemoryProviderCatalogReadRepository, ProviderCatalogReadRepository, StoredProviderCatalogKey,
+use aether_data::repository::provider_catalog::InMemoryProviderCatalogReadRepository;
+use aether_data_contracts::repository::provider_catalog::{
+    ProviderCatalogReadRepository, StoredProviderCatalogKey,
 };
 use axum::body::Body;
 use axum::routing::any;
@@ -222,9 +223,7 @@ async fn gateway_handles_admin_adaptive_mode_returns_service_unavailable_without
     let repository = adaptive_repository_with_keys(vec![adaptive_key]);
 
     assert_adaptive_route_returns_local_503(
-        crate::data::GatewayDataState::with_provider_catalog_reader_for_tests(
-            repository,
-        ),
+        crate::data::GatewayDataState::with_provider_catalog_reader_for_tests(repository),
         http::Method::PATCH,
         "/api/admin/adaptive/keys/key-adaptive/mode",
         Some(json!({ "enabled": false, "fixed_limit": 20 })),