fix: merge 30 general improvements from release branch

Bug fixes:
- Detached context for GetAccountConcurrencyBatch (prevent all-zero on request cancel)
- Filter soft-deleted users in GetByGroupID
- Stripe CSP policy (allow Stripe.js in script-src and frame-src)
- WebSearch API key validation on save
- RECHARGING status in payment result success check
- Windows test fixes (logger Sync deadlock, config path escaping)

Feature enhancements:
- Webhook multi-instance dispatch (extractOutTradeNo + GetWebhookProvider)
- EasyPay mobile H5 payment (device param + PayURL2)
- SSE error propagation in WebSearch emulation
- AccountStatsCost DTO field for admin usage logs
- Plans sort by sort_order instead of created_at
- UsageMapHook for streaming response usage data
- apicompat Instructions field passthrough
- EffectiveLoadFactor for ops concurrency/metrics
- Usage billing RETURNING balance for notify system
- BulkUpdate mixed channel warning with details
- println to slog migration in auth cache
- Wire ProviderSet cleanup
- CI cache-dependency-path optimization

Frontend:
- Refund eligibility check per provider (canRequestRefund)
- Plan sort_order editing
- Dead code cleanup (simulate_claude_max, client_affinity)
- GroupsView platform switch guard
- channels features_config API type
- UsageView account_stats_cost export

frontend/src/views/admin/orders/AdminPaymentPlansView.vue

@@ -117,6 +117,7 @@ function getPlanNameClass(groupId: number): string {
   return group ? platformTextClass(group.platform) : 'text-gray-900 dark:text-white'
 }
 
+
 // ==================== Plans ====================
 
 const plansLoading = ref(false)
@@ -133,6 +134,7 @@ const planColumns = computed((): Column[] => [
   { key: 'price', label: t('payment.admin.price') },
   { key: 'validity_days', label: t('payment.admin.validityDays') },
   { key: 'for_sale', label: t('payment.admin.forSale') },
+  { key: 'sort_order', label: t('payment.admin.sortOrder') },
   { key: 'actions', label: t('common.actions') },
 ])
 
@@ -157,6 +159,7 @@ function openPlanEdit(plan: SubscriptionPlan | null) {
   showPlanDialog.value = true
 }
 
+
 /** Quick toggle for_sale from the list */
 async function toggleForSale(plan: SubscriptionPlan) {
   try {