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/mod.rs

@@ -11,14 +11,6 @@ use aether_data::repository::auth::{
 use aether_data::repository::auth_modules::{
     InMemoryAuthModuleReadRepository, StoredLdapModuleConfig, StoredOAuthProviderModuleConfig,
 };
-use aether_data::repository::candidates::{
-    InMemoryRequestCandidateRepository, RequestCandidateStatus, StoredRequestCandidate,
-};
-use aether_data::repository::global_models::{
-    GlobalModelReadRepository, InMemoryGlobalModelReadRepository, StoredAdminGlobalModel,
-    StoredAdminProviderModel, StoredProviderActiveGlobalModel, StoredProviderModelStats,
-    StoredPublicGlobalModel,
-};
 use aether_data::repository::management_tokens::{
     InMemoryManagementTokenRepository, ManagementTokenReadRepository, StoredManagementToken,
     StoredManagementTokenUserSummary, StoredManagementTokenWithUser,
@@ -26,17 +18,24 @@ use aether_data::repository::management_tokens::{
 use aether_data::repository::oauth_providers::{
     InMemoryOAuthProviderRepository, OAuthProviderReadRepository, StoredOAuthProviderConfig,
 };
-use aether_data::repository::provider_catalog::{
-    InMemoryProviderCatalogReadRepository, ProviderCatalogReadRepository,
-    StoredProviderCatalogEndpoint, StoredProviderCatalogKey, StoredProviderCatalogProvider,
-};
+use aether_data::repository::provider_catalog::InMemoryProviderCatalogReadRepository;
 use aether_data::repository::proxy_nodes::{
     InMemoryProxyNodeRepository, ProxyNodeReadRepository, StoredProxyNode, StoredProxyNodeEvent,
 };
-use aether_data::repository::quota::{
-    InMemoryProviderQuotaRepository, StoredProviderQuotaSnapshot,
-};
+use aether_data::repository::quota::InMemoryProviderQuotaRepository;
 use aether_data::repository::wallet::InMemoryWalletRepository;
+use aether_data_contracts::repository::{
+    candidates::{RequestCandidateStatus, StoredRequestCandidate},
+    global_models::{
+        GlobalModelReadRepository, StoredAdminGlobalModel, StoredAdminProviderModel,
+        StoredProviderActiveGlobalModel, StoredProviderModelStats, StoredPublicGlobalModel,
+    },
+    provider_catalog::{
+        ProviderCatalogReadRepository, StoredProviderCatalogEndpoint, StoredProviderCatalogKey,
+        StoredProviderCatalogProvider,
+    },
+    quota::StoredProviderQuotaSnapshot,
+};
 use axum::body::{to_bytes, Body, Bytes};
 use axum::response::Response;
 use axum::routing::{any, post};