refactor: 拆分 admin handler 大文件为模块目录，消除 shared.rs 反模式

- endpoint_keys/pool/architecture 等大文件拆分为独立模块目录
- 删除 crud/query/strategy/system 中的 shared.rs，内容归位到各自模块
- endpoints_admin/models/oauth/write 等模块拆出 payloads/responses/support 子文件
- system/core 下多个 *_routes.rs 合并到 system_routes.rs
- 更新 refactor-execution-plan 文档进度

apps/aether-gateway/src/handlers/admin/provider/oauth/dispatch/helpers.rs

@@ -0,0 +1,21 @@
+use crate::handlers::admin::shared::attach_admin_audit_response;
+use axum::{
+    body::Body,
+    response::{IntoResponse, Response},
+};
+
+pub(super) fn attach_admin_provider_oauth_audit_response(
+    response: Response<Body>,
+    event_name: &'static str,
+    action: &'static str,
+    target_type: &'static str,
+    target_id: Option<String>,
+) -> Response<Body> {
+    if !response.status().is_success() {
+        return response;
+    }
+    let Some(target_id) = target_id else {
+        return response;
+    };
+    attach_admin_audit_response(response, event_name, action, target_type, &target_id)
+}