Clarify cross-site signup messaging and pass domain on login.

Also strengthen the businesses three-dot menu glass background.

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

apps/customer/src/pages/LoginPage.tsx

@@ -108,8 +108,18 @@ export function LoginPage() {
         err.message.includes('Unable to send SMS')
       ) {
         setError(t('login.error.smsProvider'))
-      } else if (err.message.includes('Cell number exists on another account')) {
-        setError(t('signup.error.cellExists'))
+      } else if (
+        err.message.includes('CELL_EXISTS_OTHER_SITE:') ||
+        err.message.includes('Cell number exists on another account')
+      ) {
+        const sites = err.message.startsWith('CELL_EXISTS_OTHER_SITE:')
+          ? err.message.slice('CELL_EXISTS_OTHER_SITE:'.length).trim()
+          : ''
+        setError(
+          sites
+            ? t('signup.error.cellExists', { sites })
+            : t('signup.error.cellExistsGeneric'),
+        )
       } else {
         setError(err.message)
       }