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/GroupsView.vue

@@ -3253,6 +3253,7 @@ const editForm = reactive({
   fallback_group_id_on_invalid_request: null as number | null,
   // OpenAI Messages 调度配置（仅 openai 平台使用）
   allow_messages_dispatch: false,
+  default_mapped_model: '',
   opus_mapped_model: editMessagesDispatchDefaults.opus_mapped_model,
   sonnet_mapped_model: editMessagesDispatchDefaults.sonnet_mapped_model,
   haiku_mapped_model: editMessagesDispatchDefaults.haiku_mapped_model,
@@ -3732,6 +3733,19 @@ watch(
   },
 );
 
+watch(
+  () => editForm.platform,
+  (newVal) => {
+    if (!['anthropic', 'antigravity'].includes(newVal)) {
+      editForm.fallback_group_id_on_invalid_request = null
+    }
+    if (newVal !== 'openai') {
+      editForm.allow_messages_dispatch = false
+      editForm.default_mapped_model = ''
+    }
+  }
+)
+
 // 点击外部关闭账号搜索下拉框
 const handleClickOutside = (event: MouseEvent) => {
   const target = event.target as HTMLElement;