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/handlers/admin/provider/oauth/dispatch/tasks.rs

@@ -1,9 +1,8 @@
-use super::super::refresh::build_internal_control_error_response;
-use super::super::state::read_provider_oauth_batch_task_payload;
-use crate::control::GatewayPublicRequestContext;
+use super::super::errors::build_internal_control_error_response;
 use crate::handlers::admin::provider::shared::paths::admin_provider_oauth_batch_import_task_path;
+use crate::handlers::admin::request::{AdminAppState, AdminRequestContext};
 use crate::handlers::admin::shared::attach_admin_audit_response;
-use crate::{AppState, GatewayError};
+use crate::GatewayError;
 use axum::{
     body::Body,
     http,
@@ -12,18 +11,20 @@ use axum::{
 };
 
 pub(super) async fn handle_admin_provider_oauth_batch_import_task_status(
-    state: &AppState,
-    request_context: &GatewayPublicRequestContext,
+    state: &AdminAppState<'_>,
+    request_context: &AdminRequestContext<'_>,
 ) -> Result<Response<Body>, GatewayError> {
     let Some((provider_id, task_id)) =
-        admin_provider_oauth_batch_import_task_path(&request_context.request_path)
+        admin_provider_oauth_batch_import_task_path(request_context.path())
     else {
         return Ok(build_internal_control_error_response(
             http::StatusCode::NOT_FOUND,
             "批量导入任务不存在",
         ));
     };
-    let payload = match read_provider_oauth_batch_task_payload(state, &provider_id, &task_id).await
+    let payload = match state
+        .read_provider_oauth_batch_task_payload(&provider_id, &task_id)
+        .await
     {
         Ok(Some(payload)) => payload,
         Ok(None) => {