Adopt shared WebUI structural primitives

webui/src/styles/mail-profiles.css

@@ -186,14 +186,6 @@
   gap: 18px;
 }
 
-.mailbox-toolbar,
-.mailbox-message-toolbar {
-  display: flex;
-  align-items: center;
-  gap: 12px;
-  justify-content: space-between;
-}
-
 .mailbox-toolbar label {
   display: grid;
   gap: 5px;
@@ -396,8 +388,7 @@
 }
 
 @media (max-width: 760px) {
-  .mailbox-toolbar,
-  .mailbox-message-toolbar {
+  .mailbox-toolbar {
     align-items: stretch;
     flex-direction: column;
   }
@@ -458,13 +449,6 @@
 
 .mailbox-folder-count {
   flex: 0 0 auto;
-  min-width: 20px;
-  padding: 1px 6px;
-  border: var(--border-line);
-  border-radius: 999px;
-  background: var(--surface-subtle);
-  color: var(--text);
-  text-align: center;
 }
 
 .mailbox-toolbar.file-manager-toolbar {