Fix email editor-email discrepancies (#15436)

Fix https://github.com/twentyhq/twenty/issues/15346

- email not centered
- reduced title sizes
- made paragraph line height and margin consistent with editor
- display line jumps

Editor
<img width="1505" height="701" alt="Capture d’écran 2025-10-29 à 16 46
20"
src="https://github.com/user-attachments/assets/5f6c6377-62b2-4697-861e-39a648cd48bb"
/>

Email
<img width="1505" height="648" alt="Capture d’écran 2025-10-29 à 16 46
36"
src="https://github.com/user-attachments/assets/a596acd8-567f-4726-996c-248519b250c5"
/>

packages/twenty-front/src/modules/advanced-text-editor/components/AdvancedTextEditor.tsx

@@ -21,8 +21,6 @@ const StyledEditorContainer = styled.div<{
     width: 100%;
     height: 100%;
     min-height: ${({ minHeight }) => minHeight}px;
-    max-width: ${({ maxWidth }) => maxWidth}px;
-    margin: 0 auto;
   }
 
   .tiptap {
@@ -56,15 +54,15 @@ const StyledEditorContainer = styled.div<{
     }
 
     h1 {
-      font-size: 36px;
+      font-size: 32px;
     }
 
     h2 {
-      font-size: 30px;
+      font-size: 24px;
     }
 
     h3 {
-      font-size: 24px;
+      font-size: 16px;
     }
 
     li {