feat: add admin reset subscription quota endpoint and UI

- Add AdminResetQuota service method to reset daily/weekly usage windows
- Add POST /api/v1/admin/subscriptions/:id/reset-quota handler and route
- Add resetQuota API function in frontend subscriptions client
- Add reset quota button, confirmation dialog, and handlers in SubscriptionsView
- Add i18n keys for reset quota feature in zh and en locales

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/admin/subscriptions.ts

@@ -120,6 +120,23 @@ export async function revoke(id: number): Promise<{ message: string }> {
   return data
 }
 
+/**
+ * Reset daily and/or weekly usage quota for a subscription
+ * @param id - Subscription ID
+ * @param options - Which windows to reset
+ * @returns Updated subscription
+ */
+export async function resetQuota(
+  id: number,
+  options: { daily: boolean; weekly: boolean }
+): Promise<UserSubscription> {
+  const { data } = await apiClient.post<UserSubscription>(
+    `/admin/subscriptions/${id}/reset-quota`,
+    options
+  )
+  return data
+}
+
 /**
  * List subscriptions by group
  * @param groupId - Group ID
@@ -170,6 +187,7 @@ export const subscriptionsAPI = {
   bulkAssign,
   extend,
   revoke,
+  resetQuota,
   listByGroup,
   listByUser
 }