Refactor models and routes for item management

Reorganized model structure by replacing 'object' and 'items' with a unified 'item' model using UUIDs, and moved base model logic into separate files. Updated routes to use the new item model and improved request/response handling. Enhanced user and setting models, added utility functions, and improved error handling throughout the codebase. Also added initial .idea project files and minor admin API improvements.

Co-Authored-By: 砂糖橘 <54745033+Foxerine@users.noreply.github.com>

.idea/.gitignore

@@ -0,0 +1,8 @@
+# 默认忽略的文件
+/shelf/
+/workspace.xml
+# 基于编辑器的 HTTP 客户端请求
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml