feat: 重要通知模块、Server 酱独立配置与额度提醒

- 新增重要通知统一模块（邮件 + Server 酱）作为后台任务通知出口
- 拆出独立的 Server 酱 配置页（SendKey + Markdown 模板，支持 {title}/{body} 变量替换），通过仪表盘内置工具入口进入
- 新增提供商额度提醒后台 worker：余额低于阈值时通过重要通知推送，提供商配置页加入额度提醒开关与阈值
- 重要通知页加入配置可用性守卫：未配置任一通道时禁用总开关，未配置邮件/SendKey 时禁用对应通道开关
- 测试通知端点支持 channel 过滤（all/email/server_chan），并绕过总开关与通道开关，便于配置阶段先验证通道
- 修复：测试通知路由未在 buffered-body 白名单导致 channel 参数丢失、测试时邮件分支被误触发
- 修复：sub2api 验证响应中 username 为 null 时正确回退到 email，避免误报"验证响应缺少: 用户信息"

Co-Authored-By: Claude Opus 4.7 <[email protected]>

apps/aether-gateway/src/handlers/admin/provider/ops/providers/config.rs

@@ -1,4 +1,7 @@
-use super::support::{AdminProviderOpsSaveConfigRequest, ADMIN_PROVIDER_OPS_SENSITIVE_FIELDS};
+use super::support::{
+    AdminProviderOpsQuotaAlertConfigRequest, AdminProviderOpsSaveConfigRequest,
+    ADMIN_PROVIDER_OPS_SENSITIVE_FIELDS,
+};
 use crate::handlers::admin::request::AdminAppState;
 use crate::GatewayError;
 use aether_admin::provider::ops as admin_provider_ops_pure;
@@ -8,6 +11,10 @@ use aether_data_contracts::repository::provider_catalog::{
 use serde_json::json;
 use std::time::{SystemTime, UNIX_EPOCH};
 
+const PROVIDER_OPS_QUOTA_ALERT_DEFAULT_FETCH_INTERVAL_SECS: u64 = 30;
+const PROVIDER_OPS_QUOTA_ALERT_MIN_FETCH_INTERVAL_SECS: u64 = 30;
+const PROVIDER_OPS_QUOTA_ALERT_MAX_FETCH_INTERVAL_SECS: u64 = 86_400;
+
 pub(super) fn admin_provider_ops_config_object(
     provider: &StoredProviderCatalogProvider,
 ) -> Option<&serde_json::Map<String, serde_json::Value>> {
@@ -276,6 +283,7 @@ pub(super) fn build_admin_provider_ops_saved_config_value(
             )
         })
         .collect::<serde_json::Map<String, serde_json::Value>>();
+    let quota_alert = normalize_admin_provider_ops_quota_alert(payload.quota_alert)?;
 
     Ok(json!({
         "architecture_id": payload.architecture_id,
@@ -287,9 +295,48 @@ pub(super) fn build_admin_provider_ops_saved_config_value(
         },
         "actions": actions,
         "schedule": payload.schedule,
+        "quota_alert": quota_alert,
     }))
 }
 
+fn normalize_admin_provider_ops_quota_alert(
+    request: Option<AdminProviderOpsQuotaAlertConfigRequest>,
+) -> Result<serde_json::Value, String> {
+    let Some(request) = request else {
+        return Ok(default_admin_provider_ops_quota_alert());
+    };
+    let threshold_amount = request.threshold_amount.unwrap_or(0.0);
+    if threshold_amount < 0.0 {
+        return Err("quota_alert.threshold_amount 必须大于等于 0".to_string());
+    }
+    let fetch_interval_seconds = request
+        .fetch_interval_seconds
+        .unwrap_or(PROVIDER_OPS_QUOTA_ALERT_DEFAULT_FETCH_INTERVAL_SECS);
+    if !(PROVIDER_OPS_QUOTA_ALERT_MIN_FETCH_INTERVAL_SECS
+        ..=PROVIDER_OPS_QUOTA_ALERT_MAX_FETCH_INTERVAL_SECS)
+        .contains(&fetch_interval_seconds)
+    {
+        return Err(format!(
+            "quota_alert.fetch_interval_seconds 必须在 {} 到 {} 秒之间",
+            PROVIDER_OPS_QUOTA_ALERT_MIN_FETCH_INTERVAL_SECS,
+            PROVIDER_OPS_QUOTA_ALERT_MAX_FETCH_INTERVAL_SECS
+        ));
+    }
+    Ok(json!({
+        "enabled": request.enabled,
+        "threshold_amount": threshold_amount,
+        "fetch_interval_seconds": fetch_interval_seconds,
+    }))
+}
+
+fn default_admin_provider_ops_quota_alert() -> serde_json::Value {
+    json!({
+        "enabled": false,
+        "threshold_amount": 0.0,
+        "fetch_interval_seconds": PROVIDER_OPS_QUOTA_ALERT_DEFAULT_FETCH_INTERVAL_SECS,
+    })
+}
+
 pub(super) fn resolve_admin_provider_ops_base_url(
     provider: &StoredProviderCatalogProvider,
     endpoints: &[StoredProviderCatalogEndpoint],
@@ -356,5 +403,10 @@ pub(super) fn build_admin_provider_ops_config_payload(
                 connector.and_then(|connector| connector.get("credentials")),
             ),
         },
+        "quota_alert": provider_ops_config
+            .get("quota_alert")
+            .filter(|value| value.is_object())
+            .cloned()
+            .unwrap_or_else(default_admin_provider_ops_quota_alert),
     })
 }