feat: provider api_formats 可空继承、OpenAI 图片 edit/variation 与用量配额多项补强

- 鉴权: provider_api_keys.api_formats 改为可空，OAuth 托管 key 自动继承 provider endpoints 激活格式，相关 handler/测试同步更新
- 图片 planner: OpenAI 图片路由新增 edit/variation 操作并完善参数校验、响应合并与流式处理
- 用量: user me usage 返回区分 client_requested_stream/upstream_is_stream，前端 usage 列表筛选与展示增强
- 统计: stats_daily_model 新增 cache_creation_ephemeral_5m/1h tokens 字段与回填链路
- 配额/observability: quota repository 新增内存与 SQL 扩展，admin observability usage 字段扩充
- 其它: OAuth 导入/轮询收敛、provider 汇总与 pool admin 读写链路小修、新增 system_config 缓存与 provider template handler

Closes #318

Co-authored-by: Entropy.Xu <[email protected]>

apps/aether-gateway/src/state/app.rs

@@ -7,7 +7,7 @@ use aether_runtime::{ConcurrencyGate, DistributedConcurrencyGate};
 use super::super::async_task::{VideoTaskPollerConfig, VideoTaskService};
 use super::super::cache::{
     AuthApiKeyLastUsedCache, AuthContextCache, DashboardResponseCache, DirectPlanBypassCache,
-    SchedulerAffinityCache,
+    SchedulerAffinityCache, SystemConfigCache,
 };
 use super::super::data::GatewayDataState;
 use super::super::fallback_metrics;
@@ -59,6 +59,7 @@ pub struct AppState {
     pub(crate) direct_plan_bypass_cache: Arc<DirectPlanBypassCache>,
     pub(crate) scheduler_affinity_cache: Arc<SchedulerAffinityCache>,
     pub(crate) dashboard_response_cache: Arc<DashboardResponseCache>,
+    pub(crate) system_config_cache: Arc<SystemConfigCache>,
     pub(crate) fallback_metrics: Arc<fallback_metrics::GatewayFallbackMetrics>,
     pub(crate) frontdoor_cors: Option<Arc<FrontdoorCorsConfig>>,
     pub(crate) frontdoor_user_rpm: Arc<FrontdoorUserRpmLimiter>,