feat(ui): display frontmatter in StructuredInfoPane

Add UI support to render frontmatter results in the document info pane, including styled header and monospace formatting.

Author: phodal

mpp-ui/src/commonMain/kotlin/cc/unitmesh/devins/ui/compose/document/StructuredInfoPane.kt

@@ -8,6 +8,7 @@ import androidx.compose.material3.*
 import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.font.FontFamily
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
@@ -557,7 +558,31 @@ private fun DocQLResultView(
                         Text(
                             text = result.tree,
                             style = MaterialTheme.typography.bodySmall,
-                            fontFamily = androidx.compose.ui.text.font.FontFamily.Monospace,
+                            fontFamily = FontFamily.Monospace,
+                            modifier = Modifier.padding(12.dp)
+                        )
+                    }
+                }
+            }
+
+            is DocQLResult.Frontmatter -> {
+                Column(modifier = Modifier.fillMaxSize()) {
+                    Text(
+                        text = "Frontmatter",
+                        style = MaterialTheme.typography.labelMedium,
+                        color = MaterialTheme.colorScheme.onSurfaceVariant,
+                        modifier = Modifier.padding(bottom = 8.dp)
+                    )
+                    Card(
+                        modifier = Modifier.fillMaxWidth(),
+                        colors = CardDefaults.cardColors(
+                            containerColor = MaterialTheme.colorScheme.surfaceVariant
+                        )
+                    ) {
+                        Text(
+                            text = result.data.toString(),
+                            style = MaterialTheme.typography.bodySmall,
+                            fontFamily = FontFamily.Monospace,
                             modifier = Modifier.padding(12.dp)
                         )
                     }