Fix icon circle collapsing narrow in strict HTML-attribute-stripping renderers

The width="56" height="56" HTML attributes on the icon badge <td> weren't
mirrored in its inline style — renderers that ignore/strip HTML
width/height (Brevo's own editor among them, per a real report) shrink
the cell to fit the glyph instead of staying a 56px circle. Add explicit
width:56px;height:56px to the style too.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/emailTemplates.ts

@@ -130,7 +130,7 @@ function emailShell(icon: string, headingHtml: string, bodyHtml: string, footerT
             <td style="text-align:center;padding-bottom:20px;">
               <table role="presentation" cellpadding="0" cellspacing="0" style="margin:0 auto;">
                 <tr>
-                  <td width="56" height="56" style="background:${BRAND}1a;border-radius:50%;text-align:center;vertical-align:middle;font-size:24px;color:${BRAND};">
+                  <td width="56" height="56" style="width:56px;height:56px;background:${BRAND}1a;border-radius:50%;text-align:center;vertical-align:middle;font-size:24px;color:${BRAND};">
                     ${icon}
                   </td>
                 </tr>