chore(editor): 清理 TimelineNameCache 未使用变量和冗余 meta 文件

- 删除未使用的 CacheFolderRelativePath 字段
- 删除 timeline_name_cache.json.meta 文件（对应 json 已不存在）

Made-with: Cursor

Assets/Editor/TimelineNameCollector/Cache/timeline_name_cache.json.meta

@@ -1,7 +0,0 @@
-fileFormatVersion: 2
-guid: 65cb908453570044abbc145dac80f6de
-TextScriptImporter:
-  externalObjects: {}
-  userData: 
-  assetBundleName: 
-  assetBundleVariant: 

Assets/Editor/TimelineNameCollector/TimelineNameCache.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Security.Cryptography;
@@ -31,7 +31,6 @@ namespace AibisDream.EditorTools
         public string lastFullScanTime;
         public List<TimelineNameCacheEntry> entries = new List<TimelineNameCacheEntry>();
 
-        private static readonly string CacheFolderRelativePath = "Assets/Editor/TimelineNameCollector/Cache";
         private static readonly string CacheFileName = "timeline_name_cache.json";
 
         public static string CacheFolderFullPath =>