feat(flutter): 剧场搜索框改白底并新增榜单新剧预约页

lib/core/widgets/plain_page_scaffold.dart

@@ -0,0 +1,80 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+
+import '../theme/app_colors.dart';
+
+/// 二级页面通用骨架：返回栏 + 标题/副标题 + 可滚动内容，无底部导航。
+class PlainPageScaffold extends StatelessWidget {
+  const PlainPageScaffold({
+    super.key,
+    required this.pageKey,
+    required this.backKey,
+    required this.title,
+    required this.child,
+    this.subtitle,
+  });
+
+  final Key pageKey;
+  final Key backKey;
+  final String title;
+  final String? subtitle;
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      key: pageKey,
+      backgroundColor: AppColors.ink,
+      body: SafeArea(
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Padding(
+              padding: const EdgeInsets.fromLTRB(6, 4, 14, 0),
+              child: Row(
+                children: [
+                  IconButton(
+                    key: backKey,
+                    tooltip: MaterialLocalizations.of(
+                      context,
+                    ).backButtonTooltip,
+                    onPressed: () => Navigator.of(context).maybePop(),
+                    icon: const Icon(
+                      Icons.chevron_left_rounded,
+                      color: AppColors.onSurface,
+                      size: 26,
+                    ),
+                  ),
+                  Expanded(
+                    child: Text(
+                      title,
+                      maxLines: 1,
+                      overflow: TextOverflow.ellipsis,
+                      style: const TextStyle(
+                        color: AppColors.onSurface,
+                        fontSize: 20,
+                        fontWeight: FontWeight.w800,
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+            if (subtitle != null)
+              Padding(
+                padding: const EdgeInsets.fromLTRB(16, 0, 16, 8),
+                child: Text(
+                  subtitle!,
+                  maxLines: 2,
+                  overflow: TextOverflow.ellipsis,
+                  style: const TextStyle(color: AppColors.muted, fontSize: 12),
+                ),
+              ),
+            Expanded(child: child),
+          ],
+        ),
+      ),
+    );
+  }
+}