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/execution_runtime/sync/execution.rs

@@ -8,8 +8,10 @@ use axum::http::Response;
 use base64::Engine as _;
 use tracing::warn;
 
-use crate::ai_pipeline::contracts::implicit_sync_finalize_report_kind;
-use crate::ai_pipeline::finalize::maybe_build_sync_finalize_outcome;
+use crate::ai_pipeline_api::{
+    implicit_sync_finalize_report_kind, maybe_build_sync_finalize_outcome,
+    LocalCoreSyncFinalizeOutcome,
+};
 use crate::api::response::{
     attach_control_metadata_headers, build_client_response, build_client_response_from_parts,
 };
@@ -46,7 +48,7 @@ pub(crate) use response::{
 
 struct ImplicitSyncFinalizeOutcome {
     payload: GatewaySyncReportRequest,
-    outcome: crate::ai_pipeline::finalize::LocalCoreSyncFinalizeOutcome,
+    outcome: LocalCoreSyncFinalizeOutcome,
 }
 
 async fn record_sync_terminal_usage(