feat(security): harden gateway boundaries and usage policies

Consolidate subscription usage policy enforcement, privacy-safe persistence, and gateway security hardening into one reviewable change.

Includes bounded HTTP and execution envelopes, header and protocol guards, DNS and relay validation, authentication and secret projection hardening, secure backup/install paths, and regression coverage.

frontend/src/views/admin/Users.vue

@@ -247,6 +247,11 @@ import {
 } from '@/features/users/components/user-management-config'
 import WalletOpsDrawer from '@/features/wallet/components/WalletOpsDrawer.vue'
 import { parseApiError } from '@/utils/errorParser'
+import {
+  entitlementsWillReplaceExisting,
+  isPlanEntitlementReplacementCandidate,
+  usagePolicyEntitlementLabels,
+} from '@/utils/billingEntitlements'
 import { formatTokens, formatRateLimitInheritable, formatRateLimitSimple, isRateLimitInherited, isRateLimitUnlimited } from '@/utils/format'
 import { log } from '@/utils/logger'
 import { useBatchSelection } from '@/composables/useBatchSelection'
@@ -558,7 +563,7 @@ function formatPlanDuration(plan: BillingPlan): string {
 }
 
 function entitlementLabels(items: BillingEntitlement[] | undefined): string[] {
-  return (items || []).map((item) => {
+  return (items || []).flatMap((item) => {
     if (item.type === 'wallet_credit') {
       return `${legacyT('附赠余额')} $${Number(item.amount_usd || 0).toFixed(2)}`
     }
@@ -568,12 +573,19 @@ function entitlementLabels(items: BillingEntitlement[] | undefined): string[] {
     if (item.type === 'membership_group') {
       return legacyT('会员权益')
     }
-    return item.type
+    if (item.type === 'usage_policy') {
+      return usagePolicyEntitlementLabels(item)
+    }
+    return []
   })
 }
 
 function hasPackageEntitlement(items: BillingEntitlement[] | undefined): boolean {
-  return (items || []).some((item) => item.type === 'daily_quota' || item.type === 'membership_group')
+  return (items || []).some((item) =>
+    item.type === 'daily_quota'
+    || item.type === 'membership_group'
+    || item.type === 'usage_policy'
+  )
 }
 
 async function loadUserWallets(options: { cacheTtlMs?: number } = {}) {
@@ -869,6 +881,21 @@ async function loadAvailableBillingPlans() {
 
 async function grantPlanToSelectedUser() {
   if (!selectedUser.value || !selectedGrantPlanId.value) return
+  const selectedPlan = availableBillingPlans.value.find(
+    plan => plan.id === selectedGrantPlanId.value,
+  )
+  const replacesExisting = selectedPlan && userPlanEntitlements.value.some(item =>
+    isPlanEntitlementReplacementCandidate(item)
+    && entitlementsWillReplaceExisting(selectedPlan.entitlements, item.entitlements)
+  )
+  if (replacesExisting) {
+    const confirmed = await confirmDanger(
+      legacyT('发放成功后，冲突的旧套餐及其组合权益会整包失效。确定继续发放吗？'),
+      legacyT('确认替换旧套餐'),
+      legacyT('继续发放'),
+    )
+    if (!confirmed) return
+  }
   grantingUserPlan.value = true
   try {
     const response = await usersApi.grantUserPlan(selectedUser.value.id, {