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/state/integrations.rs

@@ -1,17 +1,17 @@
 use std::time::Duration;
 
 use aether_contracts::{ExecutionPlan, ExecutionResult, ProxySnapshot};
-use aether_data::repository::candidate_selection::StoredMinimalCandidateSelectionRow;
-use aether_data::repository::candidates::{StoredRequestCandidate, UpsertRequestCandidateRecord};
-use aether_data::repository::global_models::{
+use aether_data_contracts::repository::candidates::{
+    StoredRequestCandidate, UpsertRequestCandidateRecord,
+};
+use aether_data_contracts::repository::global_models::{
     AdminGlobalModelListQuery, AdminProviderModelListQuery, StoredAdminGlobalModelPage,
     StoredAdminProviderModel, UpsertAdminProviderModelRecord,
 };
-use aether_data::repository::provider_catalog::{
+use aether_data_contracts::repository::provider_catalog::{
     StoredProviderCatalogEndpoint, StoredProviderCatalogKey, StoredProviderCatalogProvider,
 };
-use aether_data::repository::quota::StoredProviderQuotaSnapshot;
-use aether_data::DataLayerError;
+use aether_data_contracts::repository::quota::StoredProviderQuotaSnapshot;
 use aether_model_fetch::{
     aggregate_models_for_cache, model_fetch_interval_minutes, ModelFetchAssociationStore,
     ModelFetchTransportRuntime,
@@ -27,10 +27,10 @@ use crate::provider_transport::{
     resolve_transport_proxy_snapshot_with_tunnel_affinity, GatewayProviderTransportSnapshot,
     LocalResolvedOAuthRequestAuth,
 };
-use crate::scheduler::{
-    GatewayMinimalCandidateSelectionCandidate, SchedulerCandidateSelectionRowSource,
-    SchedulerRequestCandidateRuntimeState, SchedulerRuntimeState,
+use crate::request_candidate_runtime::{
+    RequestCandidateRuntimeReader, RequestCandidateRuntimeWriter,
 };
+use crate::scheduler::state::SchedulerRuntimeState;
 use crate::{execution_runtime, provider_transport};
 
 #[async_trait]
@@ -237,17 +237,20 @@ impl ModelFetchAssociationStore for AppState {
 }
 
 #[async_trait]
-impl SchedulerRequestCandidateRuntimeState for AppState {
-    fn has_request_candidate_data_writer(&self) -> bool {
-        AppState::has_request_candidate_data_writer(self)
-    }
-
+impl RequestCandidateRuntimeReader for AppState {
     async fn read_request_candidates_by_request_id(
         &self,
         request_id: &str,
     ) -> Result<Vec<StoredRequestCandidate>, GatewayError> {
         AppState::read_request_candidates_by_request_id(self, request_id).await
     }
+}
+
+#[async_trait]
+impl RequestCandidateRuntimeWriter for AppState {
+    fn has_request_candidate_data_writer(&self) -> bool {
+        AppState::has_request_candidate_data_writer(self)
+    }
 
     async fn upsert_request_candidate(
         &self,
@@ -257,28 +260,6 @@ impl SchedulerRequestCandidateRuntimeState for AppState {
     }
 }
 
-#[async_trait]
-impl SchedulerCandidateSelectionRowSource for AppState {
-    async fn read_minimal_candidate_selection_rows_for_api_format_and_global_model(
-        &self,
-        api_format: &str,
-        global_model_name: &str,
-    ) -> Result<Vec<StoredMinimalCandidateSelectionRow>, DataLayerError> {
-        self.data
-            .list_minimal_candidate_selection_rows(api_format, global_model_name)
-            .await
-    }
-
-    async fn read_minimal_candidate_selection_rows_for_api_format(
-        &self,
-        api_format: &str,
-    ) -> Result<Vec<StoredMinimalCandidateSelectionRow>, DataLayerError> {
-        self.data
-            .list_minimal_candidate_selection_rows_for_api_format(api_format)
-            .await
-    }
-}
-
 #[async_trait]
 impl SchedulerRuntimeState for AppState {
     async fn read_provider_quota_snapshot(
@@ -309,23 +290,6 @@ impl SchedulerRuntimeState for AppState {
         AppState::read_recent_request_candidates(self, limit).await
     }
 
-    async fn read_minimal_candidate_selection(
-        &self,
-        api_format: &str,
-        global_model_name: &str,
-        require_streaming: bool,
-        auth_snapshot: Option<&crate::data::auth::GatewayAuthApiKeySnapshot>,
-    ) -> Result<Vec<GatewayMinimalCandidateSelectionCandidate>, GatewayError> {
-        AppState::read_minimal_candidate_selection(
-            self,
-            api_format,
-            global_model_name,
-            require_streaming,
-            auth_snapshot,
-        )
-        .await
-    }
-
     fn provider_key_rpm_reset_at(&self, key_id: &str, now_unix_secs: u64) -> Option<u64> {
         AppState::provider_key_rpm_reset_at(self, key_id, now_unix_secs)
     }