fix(maestro): show tool icon in attach header instead of raw command

Session header used to print the raw command line ("claude"); mirror
the sidebar's icon-for-program treatment so both agree.

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

web/src/styles.css

@@ -1279,6 +1279,9 @@ input.leaf-rename:focus {
 
 .attach-title .at-cmd {
   color: var(--muted);
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
 }
 
 .attach-title .at-cmd::before {