fix(theme): use theme border token for preview swatches and add mono fallback (#1654)

lib/features/settings/theme_editor_dialog.dart

@@ -344,6 +344,7 @@ class _ThemeEditorColorRow extends material.StatelessWidget {
                 fontSize: 12,
                 color: cs.mutedForeground,
                 fontFamily: QueryaTypography.mono,
+                fontFamilyFallback: QueryaTypography.monoFontFamilyFallback,
               ),
             ),
           ),

lib/features/settings/theme_preview_card.dart

@@ -223,7 +223,7 @@ class _Swatch extends material.StatelessWidget {
             color: color,
             borderRadius: material.BorderRadius.circular(radius),
             border: material.Border.all(
-              color: material.Colors.black.withValues(alpha: 0.12),
+              color: Theme.of(context).colorScheme.border.withValues(alpha: 0.6),
             ),
           ),
         ),

test/features/settings/theme_editor_dialog_test.dart

@@ -102,6 +102,14 @@ void main() {
         expect(find.text(field.label), findsWidgets);
       }
 
+      // Verify hex label uses mono font and fallback
+      final hexTextFinder = find.byWidgetPredicate((widget) {
+        return widget is material.Text &&
+            widget.style?.fontFamily == 'Cascadia Code' &&
+            widget.style?.fontFamilyFallback?.contains('Consolas') == true;
+      });
+      expect(hexTextFinder, findsWidgets);
+
       // Close modal
       await tester.tap(find.text('Done'));
       await tester.pumpAndSettle();

test/features/settings/theme_preview_card_test.dart

@@ -40,6 +40,25 @@ void main() {
       expect(find.text('Surface'), findsOneWidget);
       expect(find.text('Primary'), findsOneWidget);
       expect(find.text('Accent'), findsOneWidget);
+
+      // Verify swatch border uses theme border token with alpha
+      final containers = tester
+          .widgetList<material.Container>(find.byType(material.Container))
+          .where((c) {
+        final dec = c.decoration;
+        return dec is material.BoxDecoration && dec.border is material.Border;
+      }).toList();
+
+      final swatchBox = containers.firstWhere((c) {
+        final dec = c.decoration as material.BoxDecoration;
+        return dec.borderRadius == material.BorderRadius.circular(4);
+      });
+      final border =
+          (swatchBox.decoration as material.BoxDecoration).border as material.Border;
+      expect(
+        border.top.color,
+        QueryaTheme.darkDefault.colorScheme.border.withValues(alpha: 0.6),
+      );
     });
 
     testWidgets('shows loading state', (tester) async {