fix: unify dialog layout and fix content padding issues

- Fix negative margin overflow in all dialog content areas
- Standardize dialog structure with flex-col layout
- Add consistent py-4 spacing to all content areas
- Ensure proper spacing between header, content, and footer

Affected components:
- AddProviderDialog, EditProviderDialog
- McpFormModal, McpPanel
- UsageScriptModal
- SettingsDialog

All dialogs now follow unified layout pattern:
- DialogContent: flex flex-col max-h-[90vh]
- Content area: flex-1 overflow-y-auto px-6 py-4
- No negative margins that cause content overflow

src/components/UsageFooter.tsx

@@ -15,11 +15,11 @@ const UsageFooter: React.FC<UsageFooterProps> = ({
   appType,
   usageEnabled,
 }) => {
-  const { data: usage, isLoading: loading, refetch } = useUsageQuery(
-    providerId,
-    appType,
-    usageEnabled,
-  );
+  const {
+    data: usage,
+    isLoading: loading,
+    refetch,
+  } = useUsageQuery(providerId, appType, usageEnabled);
 
   // 只在启用用量查询且有数据时显示
   if (!usageEnabled || !usage) return null;