feat(client_app): open privacy policy in in-app webview

Add a reusable WebPageScreen (webview_flutter host with close button +
progress bar, no nav interception) and wire the profile 'kebijakan privasi'
menu item to open https://mybestieindonesia.com/privacy in it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client_app/lib/core/widgets/web_page_screen.dart

@@ -0,0 +1,96 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:webview_flutter/webview_flutter.dart';
+
+import '../theme/halo_tokens.dart';
+
+/// Generic in-app WebView host for static external pages (privacy policy,
+/// terms & conditions, etc).
+///
+/// Unlike [XenditCheckoutScreen] this carries no navigation-interception logic
+/// — it just loads [url] and lets the user read it, with a close button and a
+/// progress bar. Push it with a plain `Navigator.push(MaterialPageRoute(...))`.
+class WebPageScreen extends StatefulWidget {
+  final String url;
+  final String title;
+
+  const WebPageScreen({
+    super.key,
+    required this.url,
+    required this.title,
+  });
+
+  @override
+  State<WebPageScreen> createState() => _WebPageScreenState();
+}
+
+class _WebPageScreenState extends State<WebPageScreen> {
+  late final WebViewController _controller;
+  int _progress = 0;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = WebViewController()
+      ..setJavaScriptMode(JavaScriptMode.unrestricted)
+      ..setBackgroundColor(HaloTokens.surface)
+      ..setNavigationDelegate(
+        NavigationDelegate(
+          onProgress: (p) {
+            if (!mounted) return;
+            setState(() => _progress = p);
+          },
+          onWebResourceError: (error) {
+            if (kDebugMode) {
+              debugPrint(
+                '[WebPageScreen] WebResourceError '
+                'code=${error.errorCode} type=${error.errorType} '
+                'desc=${error.description} url=${error.url}',
+              );
+            }
+          },
+        ),
+      )
+      ..loadRequest(Uri.parse(widget.url));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      backgroundColor: HaloTokens.surface,
+      appBar: AppBar(
+        backgroundColor: HaloTokens.surface,
+        elevation: 0,
+        leading: IconButton(
+          icon: const Icon(Icons.close, color: HaloTokens.brandDark),
+          tooltip: 'Tutup',
+          onPressed: () => Navigator.of(context).pop(),
+        ),
+        title: Text(
+          widget.title,
+          style: const TextStyle(
+            fontFamily: HaloTokens.fontDisplay,
+            fontSize: 16,
+            fontWeight: FontWeight.w700,
+            color: HaloTokens.brandDark,
+          ),
+        ),
+        centerTitle: true,
+        bottom: _progress < 100
+            ? PreferredSize(
+                preferredSize: const Size.fromHeight(2),
+                child: LinearProgressIndicator(
+                  value: _progress / 100.0,
+                  minHeight: 2,
+                  backgroundColor: HaloTokens.brandSofter,
+                  valueColor: const AlwaysStoppedAnimation<Color>(
+                    HaloTokens.brand,
+                  ),
+                ),
+              )
+            : null,
+      ),
+      body: WebViewWidget(controller: _controller),
+    );
+  }
+}

client_app/lib/features/profile/profile_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 import '../../core/auth/auth_notifier.dart';
 import '../../core/theme/halo_tokens.dart';
+import '../../core/widgets/web_page_screen.dart';
 import '../home/widgets/halo_tab_bar.dart';
 
 /// "Kamu" tab — profile screen.
@@ -78,7 +79,14 @@ class ProfileScreen extends ConsumerWidget {
                     _MenuItemData(
                       icon: Icons.lock_outline,
                       label: 'kebijakan privasi',
-                      onTap: () {},
+                      onTap: () => Navigator.of(context).push(
+                        MaterialPageRoute(
+                          builder: (_) => const WebPageScreen(
+                            url: 'https://mybestieindonesia.com/privacy',
+                            title: 'kebijakan privasi',
+                          ),
+                        ),
+                      ),
                     ),
                   ]),
                   const SizedBox(height: 16),