refactor: 拆分 gateway 单体为独立 crate，新增 systemd 部署方案

将 gateway 内部的 model-fetch、provider-transport、scheduler-core、
usage-runtime、video-tasks-core 模块提取为独立 crate；重构 gateway
内部模块结构（state/router/cache/data/query 等）；移除大量遗留模块
文件；新增 systemd 二进制部署骨架及相关文档；更新前端 usage 相关
API 和组件。

apps/aether-gateway/src/wallet_runtime/access.rs

@@ -3,12 +3,13 @@ use aether_wallet::{
     WalletAccessDecision, WalletAccessFailure, WalletLimitMode, WalletSnapshot, WalletStatus,
 };
 
-use crate::gateway::gateway_data::StoredGatewayAuthApiKeySnapshot;
-use crate::gateway::{AppState, GatewayError, GatewayLocalAuthRejection};
+use crate::control::GatewayLocalAuthRejection;
+use crate::data::auth::GatewayAuthApiKeySnapshot;
+use crate::{AppState, GatewayError};
 
 pub(crate) async fn resolve_wallet_auth_gate(
     state: &AppState,
-    auth_snapshot: &StoredGatewayAuthApiKeySnapshot,
+    auth_snapshot: &GatewayAuthApiKeySnapshot,
 ) -> Result<Option<WalletAccessDecision>, GatewayError> {
     if !state.has_wallet_data_reader() {
         return Ok(None);
@@ -65,7 +66,7 @@ mod tests {
     use aether_wallet::{WalletAccessFailure, WalletLimitMode, WalletSnapshot, WalletStatus};
 
     use super::{local_rejection_from_wallet_access, map_wallet_snapshot};
-    use crate::gateway::GatewayLocalAuthRejection;
+    use crate::control::GatewayLocalAuthRejection;
 
     #[test]
     fn maps_wallet_snapshot_and_derives_balance_denied() {