style(tui): distinguish markdown h1 headings (#27814)

packages/opencode/src/cli/cmd/tui/context/theme.tsx

@@ -962,6 +962,7 @@ function getSyntaxRules(theme: Theme) {
       style: {
         foreground: theme.markdownHeading,
         bold: true,
+        underline: true,
       },
     },
     {