Polish email template system with UX improvements

- Consolidated multiple preview canvases into single shared preview with "Simpan & Preview" button
- Fixed double scrollbar issue in preview box by using fixed height container and scrolling=no
- Added modular email components to Tiptap editor:
  * EmailButton with URL, text, and full-width options
  * OTPBox with monospace font and dashed border styling
  * EmailTable with brutalist styling and proper header support
- Generated contextual initial email content for all template types:
  * Payment success with professional details table
  * Access granted with celebration styling and prominent CTA
  * Order created with clear next steps and status information
  * Payment reminder with urgent styling and warning alerts
  * Consulting scheduled with session details and preparation tips
  * Event reminder with high-energy countdown and call-to-action
  * Bootcamp progress with motivational progress tracking
- Enhanced RichTextEditor toolbar with email component buttons and visual separators
- Improved NotifikasiTab with streamlined preview workflow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/admin/EmailTemplatePreview.tsx

@@ -134,12 +134,16 @@ export function EmailTemplatePreview({ template, onTest, isTestSending = false }
             {previewMode === 'master' ? 'Full Email Preview' : 'Content Preview'}
           </span>
         </div>
-        <div className="max-h-96 overflow-auto bg-white">
+        <div className="bg-white" style={{ height: '600px', overflow: 'hidden' }}>
           <iframe
             srcDoc={previewHtml}
-            className="w-full border-0"
-            style={{ height: '500px' }}
+            className="w-full h-full border-0"
+            style={{
+              height: '100%',
+              overflow: 'hidden'
+            }}
             sandbox="allow-same-origin"
+            scrolling="no"
           />
         </div>
       </div>