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

backend/internal/service/payment_config_plans.go

@@ -113,11 +113,11 @@ func (s *PaymentConfigService) GetGroupInfoMap(ctx context.Context, plans []*dbe
 }
 
 func (s *PaymentConfigService) ListPlans(ctx context.Context) ([]*dbent.SubscriptionPlan, error) {
-	return s.entClient.SubscriptionPlan.Query().Order(subscriptionplan.ByCreatedAt()).All(ctx)
+	return s.entClient.SubscriptionPlan.Query().Order(subscriptionplan.BySortOrder()).All(ctx)
 }
 
 func (s *PaymentConfigService) ListPlansForSale(ctx context.Context) ([]*dbent.SubscriptionPlan, error) {
-	return s.entClient.SubscriptionPlan.Query().Where(subscriptionplan.ForSaleEQ(true)).Order(subscriptionplan.ByCreatedAt()).All(ctx)
+	return s.entClient.SubscriptionPlan.Query().Where(subscriptionplan.ForSaleEQ(true)).Order(subscriptionplan.BySortOrder()).All(ctx)
 }
 
 func (s *PaymentConfigService) CreatePlan(ctx context.Context, req CreatePlanRequest) (*dbent.SubscriptionPlan, error) {