feat(config): create engagement settings form widget

    Introduces the `EngagementSettingsForm` for managing the `EngagementConfig`. This widget provides a master toggle for the engagement system and a `SegmentedButton` to switch between 'Reactions Only' and 'Reactions & Comments' modes, abstracting the engagement logic into a dedicated UI component.

Author: fulleni

lib/app_configuration/widgets/engagement_settings_form.dart

@@ -0,0 +1,88 @@
+import 'package:core/core.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/l10n/l10n.dart';
+import 'package:flutter_news_app_web_dashboard_full_source_code/shared/extensions/engagement_mode_l10n.dart';
+import 'package:ui_kit/ui_kit.dart';
+
+/// {@template engagement_settings_form}
+/// A form widget for configuring user engagement settings.
+/// {@endtemplate}
+class EngagementSettingsForm extends StatelessWidget {
+  /// {@macro engagement_settings_form}
+  const EngagementSettingsForm({
+    required this.remoteConfig,
+    required this.onConfigChanged,
+    super.key,
+  });
+
+  /// The current [RemoteConfig] object.
+  final RemoteConfig remoteConfig;
+
+  /// Callback to notify parent of changes to the [RemoteConfig].
+  final ValueChanged<RemoteConfig> onConfigChanged;
+
+  @override
+  Widget build(BuildContext context) {
+    final l10n = AppLocalizationsX(context).l10n;
+    final communityConfig = remoteConfig.features.community;
+    final engagementConfig = communityConfig.engagement;
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        SwitchListTile(
+          title: Text(l10n.enableEngagementFeaturesLabel),
+          subtitle: Text(l10n.enableEngagementFeaturesDescription),
+          value: engagementConfig.enabled,
+          onChanged: (value) {
+            final newConfig = communityConfig.copyWith(
+              engagement: engagementConfig.copyWith(enabled: value),
+            );
+            onConfigChanged(
+              remoteConfig.copyWith(
+                features: remoteConfig.features.copyWith(community: newConfig),
+              ),
+            );
+          },
+        ),
+        const SizedBox(height: AppSpacing.lg),
+        Padding(
+          padding: const EdgeInsets.symmetric(horizontal: AppSpacing.lg),
+          child: Text(
+            l10n.engagementModeDescription,
+            style: Theme.of(context).textTheme.bodySmall,
+          ),
+        ),
+        const SizedBox(height: AppSpacing.md),
+        Padding(
+          padding: const EdgeInsets.symmetric(horizontal: AppSpacing.lg),
+          child: SegmentedButton<EngagementMode>(
+            segments: EngagementMode.values
+                .map(
+                  (mode) => ButtonSegment<EngagementMode>(
+                    value: mode,
+                    label: Text(mode.l10n(context)),
+                  ),
+                )
+                .toList(),
+            selected: {engagementConfig.engagementMode},
+            onSelectionChanged: (newSelection) {
+              final newConfig = communityConfig.copyWith(
+                engagement: engagementConfig.copyWith(
+                  engagementMode: newSelection.first,
+                ),
+              );
+              onConfigChanged(
+                remoteConfig.copyWith(
+                  features: remoteConfig.features.copyWith(
+                    community: newConfig,
+                  ),
+                ),
+              );
+            },
+          ),
+        ),
+      ],
+    );
+  }
+}