Sanitize rich-text paste and allow empty business postal codes.

Strip background/font-family/colors on paste while keeping bold, lists, and font size; treat business address postal code as optional.

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/business/src/pages/BusinessProfilePage.tsx

@@ -201,7 +201,7 @@ export function BusinessProfilePage() {
                   : item.province,
                 city: item.city,
                 address: item.address,
-                postalCode: item.postalCode,
+                postalCode: item.postalCode ?? '',
                 landline: item.landline ?? '',
               }
             })
@@ -332,7 +332,7 @@ export function BusinessProfilePage() {
           province: item.province.trim(),
           city: item.city.trim(),
           address: item.address.trim(),
-          postalCode: item.postalCode.trim(),
+          postalCode: item.postalCode.trim() || undefined,
           landline: item.landline?.trim() || null,
         }))