feat: 添加画廊列表显示模式和合并功能，优化画廊列表卡片组件

lib/api/api_result.dart

@@ -27,6 +27,14 @@ class ApiResult<T> {
     }
   }
 
+  T? unwrapOrNull() {
+    if (ok) {
+      return data;
+    } else {
+      return null;
+    }
+  }
+
   (int, String) unwrapErr() {
     if (ok) {
       return throw 'unwrap_err called on ok ApiResult';

lib/api/file.dart

@@ -41,8 +41,8 @@ class EhFileExtend {
 }
 
 class EhFiles {
-  const EhFiles({required this.files});
-  final Map<String, List<EhFileBasic>> files;
+  EhFiles({required this.files});
+  Map<String, List<EhFileBasic>> files;
   factory EhFiles.fromJson(Map<String, dynamic> json) => EhFiles(
         files: (json).map(
           (k, e) => MapEntry(
@@ -52,4 +52,7 @@ class EhFiles {
                   .toList()),
         ),
       );
+  void merge(EhFiles another) {
+    files.addAll(another.files);
+  }
 }

lib/api/gallery.dart

@@ -239,10 +239,10 @@ class GMetaSearchInfo {
 }
 
 class GalleryThumbnails {
-  const GalleryThumbnails({
+  GalleryThumbnails({
     required this.thumbnails,
   });
-  final Map<int, ApiResult<ExtendedPMeta>> thumbnails;
+  Map<int, ApiResult<ExtendedPMeta>> thumbnails;
   factory GalleryThumbnails.fromJson(Map<String, dynamic> json) =>
       GalleryThumbnails(
           thumbnails: json.map((key, value) => MapEntry(
@@ -251,4 +251,17 @@ class GalleryThumbnails {
                   value as Map<String, dynamic>,
                   (json) =>
                       ExtendedPMeta.fromJson(json as Map<String, dynamic>)))));
+  void merge(GalleryThumbnails another) {
+    another.thumbnails.forEach((key, value) {
+      if (thumbnails.containsKey(key)) {
+        if (value.ok) {
+          thumbnails[key] = value;
+        } else if (!thumbnails[key]!.ok) {
+          thumbnails[key] = value;
+        }
+      } else {
+        thumbnails[key] = value;
+      }
+    });
+  }
 }