refactor: delegate filetree upload fallback

rust/crates/mnote-web/browser/filetree-runtime.js

@@ -120,6 +120,35 @@ function fileTreeChildCount(documentId, deps) {
   return children.length;
 }
 
+function fileTreeUploadTargetFallback(detail, deps) {
+  detail = detail || {};
+  deps = deps || {};
+  var resolveWorkspaceId = typeof deps.resolveWorkspaceId === 'function' ? deps.resolveWorkspaceId : function() { return ''; };
+  var currentDocumentId = typeof deps.currentDocumentId === 'function' ? deps.currentDocumentId : function() { return ''; };
+  var workspaceId = String(detail.workspaceId || resolveWorkspaceId(document.body) || '').trim();
+  var documentId = String(detail.documentId || currentDocumentId() || '').trim();
+  if (Object.prototype.hasOwnProperty.call(detail, 'targetRelativePath')) {
+    return {
+      workspaceId: workspaceId,
+      targetDocumentId: documentId,
+      targetMindmapId: null,
+      targetSubPath: null,
+      targetRelativePath: String(detail.targetRelativePath || ''),
+      uploadIntent: String(detail.uploadIntent || 'filetree.folder.drop')
+    };
+  }
+  if (!workspaceId || !documentId) {
+    throw new Error('请选择一个目标页面后再拖入文件');
+  }
+  return {
+    workspaceId: workspaceId,
+    targetDocumentId: documentId,
+    targetMindmapId: null,
+    targetSubPath: null,
+    uploadIntent: String(detail.uploadIntent || 'editor.markdown.attach')
+  };
+}
+
 window.__mnoteFileTreeRuntime = {
   fileTreeRowKind: fileTreeRowKind,
   fileTreeRowDocumentId: fileTreeRowDocumentId,
@@ -131,5 +160,6 @@ window.__mnoteFileTreeRuntime = {
   isFileTreeDownloadableRow: isFileTreeDownloadableRow,
   fileTreeAssetDownloadDetail: fileTreeAssetDownloadDetail,
   fileTreeRowsByRowIds: fileTreeRowsByRowIds,
-  fileTreeChildCount: fileTreeChildCount
+  fileTreeChildCount: fileTreeChildCount,
+  fileTreeUploadTargetFallback: fileTreeUploadTargetFallback
 };