refine: standardize provider dialog dimensions to match MCP panel

Adjusted Add and Edit provider dialogs to use consistent sizing with MCP panel:
- Increased max width from max-w-2xl to max-w-3xl
- Unified max height to max-h-[85vh] (was 90vh)
- Added min-h-[600px] for minimum height constraint

This ensures visual consistency across all major dialog panels in the app.

src/components/providers/AddProviderDialog.tsx

@@ -140,7 +140,7 @@ export function AddProviderDialog({
 
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
-      <DialogContent className="max-w-2xl max-h-[90vh] flex flex-col">
+      <DialogContent className="max-w-3xl max-h-[85vh] min-h-[600px] flex flex-col">
         <DialogHeader>
           <DialogTitle>{submitLabel}</DialogTitle>
           <DialogDescription>

src/components/providers/EditProviderDialog.tsx

@@ -63,7 +63,7 @@ export function EditProviderDialog({
 
   return (
     <Dialog open={open} onOpenChange={onOpenChange}>
-      <DialogContent className="max-w-2xl max-h-[90vh] flex flex-col">
+      <DialogContent className="max-w-3xl max-h-[85vh] min-h-[600px] flex flex-col">
         <DialogHeader>
           <DialogTitle>
             {t("provider.editProvider")}