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/tests/control/mod.rs

@@ -0,0 +1,61 @@
+use std::collections::BTreeMap;
+use std::sync::{Arc, Mutex};
+use std::time::{SystemTime, UNIX_EPOCH};
+
+use aether_crypto::{
+    decrypt_python_fernet_ciphertext, encrypt_python_fernet_plaintext, DEVELOPMENT_ENCRYPTION_KEY,
+};
+use aether_data::repository::auth::{
+    InMemoryAuthApiKeySnapshotRepository, StoredAuthApiKeySnapshot,
+};
+use aether_data::repository::auth_modules::{
+    InMemoryAuthModuleReadRepository, StoredLdapModuleConfig, StoredOAuthProviderModuleConfig,
+};
+use aether_data::repository::candidates::{
+    InMemoryRequestCandidateRepository, RequestCandidateStatus, StoredRequestCandidate,
+};
+use aether_data::repository::global_models::{
+    GlobalModelReadRepository, InMemoryGlobalModelReadRepository, StoredAdminGlobalModel,
+    StoredAdminProviderModel, StoredProviderActiveGlobalModel, StoredProviderModelStats,
+    StoredPublicGlobalModel,
+};
+use aether_data::repository::management_tokens::{
+    InMemoryManagementTokenRepository, ManagementTokenReadRepository, StoredManagementToken,
+    StoredManagementTokenUserSummary, StoredManagementTokenWithUser,
+};
+use aether_data::repository::oauth_providers::{
+    InMemoryOAuthProviderRepository, OAuthProviderReadRepository, StoredOAuthProviderConfig,
+};
+use aether_data::repository::provider_catalog::{
+    InMemoryProviderCatalogReadRepository, ProviderCatalogReadRepository,
+    StoredProviderCatalogEndpoint, StoredProviderCatalogKey, StoredProviderCatalogProvider,
+};
+use aether_data::repository::proxy_nodes::{
+    InMemoryProxyNodeRepository, ProxyNodeReadRepository, StoredProxyNode, StoredProxyNodeEvent,
+};
+use aether_data::repository::quota::{
+    InMemoryProviderQuotaRepository, StoredProviderQuotaSnapshot,
+};
+use aether_data::repository::wallet::InMemoryWalletRepository;
+use axum::body::{to_bytes, Body, Bytes};
+use axum::response::Response;
+use axum::routing::{any, post};
+use axum::{extract::Request, Json, Router};
+use http::header::{HeaderName, HeaderValue};
+use http::{HeaderMap, StatusCode};
+use serde_json::json;
+
+mod admin;
+mod helpers;
+mod internal;
+mod proxy;
+
+use super::{
+    build_router, build_router_with_execution_runtime_override, build_router_with_state,
+    build_state_with_execution_runtime_override, start_server, wait_until, AppState,
+    FrontdoorCorsConfig, FrontdoorUserRpmConfig, GatewayFallbackMetricKind, GatewayFallbackReason,
+    Infallible, UsageRuntimeConfig, VideoTaskTruthSourceMode,
+};
+use crate::constants::*;
+use crate::data::GatewayDataState;
+use helpers::*;