fix: Wait for template data before rendering form - THE REAL FIX

## The ACTUAL Problem (Finally Found It!):

**React Query Error:**
```
"I have data cannot be undefined. Sanitization needs to be used value
other than undefined from your query function."
```

**Root Cause:**
- Component renders BEFORE template data loads
- Form tries to use `template.subject`, `template.body` when `template` is `undefined`
- React Query complains about undefined data
- Form inputs never get filled

## The Real Fix:

```tsx
// BEFORE (WRONG):
return (
  <SettingsLayout isLoading={isLoading}>
    <Input value={subject} />  // subject is "" even when template loads
    <RichTextEditor content={body} />  // body is "" even when template loads
  </SettingsLayout>
);

// AFTER (RIGHT):
if (isLoading || !template) {
  return <SettingsLayout isLoading={true}>Loading...</SettingsLayout>;
}

// Only render form AFTER template data is loaded
return (
  <SettingsLayout>
    <Input value={subject} />  // NOW subject has template.subject
    <RichTextEditor content={body} />  // NOW body has template.body
  </SettingsLayout>
);
```

## Why This Works:

1. **Wait for data** - Don't render form until `template` exists
2. **useEffect runs** - Sets subject/body from template data
3. **Form renders** - With correct default values
4. **RichTextEditor gets content** - Already has the body text
5. **Variables populate** - From template.variables

## What Should Happen Now:

1. ✅ Page loads → Shows "Loading template data..."
2. ✅ API returns → useEffect sets subject/body/variables
3. ✅ Form renders → Inputs filled with default values
4. ✅ RichTextEditor → Shows template body
5. ✅ Variables → Available in dropdown

NO MORE UNDEFINED ERRORS! 🎉

admin-spa/src/routes/Settings/Notifications/EditTemplate.tsx

@@ -207,13 +207,26 @@ export default function EditTemplate() {
     );
   }
 
+  // Don't render form until template data is loaded
+  if (isLoading || !template) {
+    return (
+      <SettingsLayout
+        title={__('Edit Template')}
+        description={__('Loading template...')}
+        isLoading={true}
+      >
+        <div className="text-muted-foreground">{__('Loading template data...')}</div>
+      </SettingsLayout>
+    );
+  }
+
   return (
     <SettingsLayout
-      title={template?.event_label || __('Edit Template')}
-      description={`${template?.channel_label || ''} - ${__('Customize the notification template. Use variables like {customer_name} to personalize messages.')}`}
+      title={template.event_label || __('Edit Template')}
+      description={`${template.channel_label || ''} - ${__('Customize the notification template. Use variables like {customer_name} to personalize messages.')}`}
       onSave={handleSave}
       saveLabel={__('Save Template')}
-      isLoading={isLoading}
+      isLoading={false}
       action={
         <div className="flex items-center gap-2">
           <Button