refactor: 大规模模块拆分与重组，新增 aether-admin crate

- 新建独立 aether-admin crate 承载 admin 相关共享契约与纯辅助函数
- 拆分 ai_pipeline 下 kiro/private_envelope/conversion/planner 等大文件为子模块目录
- 重组 admin handlers 各业务域（billing/oauth/provider/system/users 等）为目录结构，移除 shared.rs/builders.rs 等反模式
- 移除 ai_pipeline runtime adapters 旧实现（claude/openai/gemini/kiro/vertex/antigravity 等），改由 provider transport 统一承载
- 移除 control_facade/execution_facade/auth_snapshot_facade 等冗余 facade 层
- 拆分 query/billing 与 query/monitoring 模块、state/runtime/payments 与 security 模块
- 扩展架构测试覆盖 admin_billing/admin_model/admin_users 等新模块
- 删除 docs/architecture/refactor-execution-plan.md 已完成的执行计划文档

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

@@ -15,8 +15,8 @@ use sqlx::Row;
 use tracing::{debug, info, warn};
 use uuid::Uuid;
 
+use crate::admin_api::admin_provider_ops_local_action_response;
 use crate::data::GatewayDataState;
-use crate::handlers::admin::provider::ops::providers::actions::admin_provider_ops_local_action_response;
 use crate::{AppState, GatewayError};
 
 #[path = "runtime/audit_cleanup.rs"]

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

@@ -6,7 +6,7 @@ use aether_data_contracts::repository::provider_catalog::{
 use futures_util::stream::{self, StreamExt};
 use tracing::{debug, warn};
 
-use crate::handlers::admin::provider::ops::providers::actions::admin_provider_ops_local_action_response;
+use crate::admin_api::{admin_provider_ops_local_action_response, AdminAppState};
 use crate::{AppState, GatewayError};
 
 use super::{system_config_bool, PROVIDER_CHECKIN_CONCURRENCY};
@@ -135,8 +135,9 @@ async fn run_provider_checkin_for_provider(
     endpoints: Vec<StoredProviderCatalogEndpoint>,
 ) -> ProviderCheckinOutcome {
     let provider_id = provider.id.clone();
+    let admin_state = AdminAppState::new(state);
     let payload = admin_provider_ops_local_action_response(
-        state,
+        &admin_state,
         &provider_id,
         Some(&provider),
         &endpoints,