#21146: Can Folder / Link sidebar menu items be created via API?

When clicking "+ New menu item" in the workspace sidebar, the dialog offers five types:

Object View Record Folder Link

I can create View favorites via createFavorite on /graphql using FavoriteCreateInput { viewId, position, forWorkspaceMemberId } — this works. Is there any API surface — /graphql, /metadata, REST, or anywhere else — to create:

A favorite Folder with a name (e.g. "E-Mail & Termine") that can hold child favorites? A Link menu item with a name + external URL (e.g. "Reports" → https://example.com/dashboard)? A favorite placed inside a specific folder (i.e. createFavorite with favoriteFolderId set — the input type accepts the field, but I can't find a way to create the folder it references)?

What I've already checked

favoriteFolders query returns totalCount: 0 even when the UI clearly shows a folder. FavoriteCreateInput has slots for viewId, taskId, companyId, personId, objektId, dashboardId, noteId, opportunityId, workflowId, favoriteFolderId, forWorkspaceMemberId — but no URL / href / link field, so createFavorite cannot store an external URL. Schema introspection of Query and Mutation types on both /graphql and /metadata returns nothing matching link, menu, nav, sidebar, bookmark beyond the favorites/folders entries above. No createFavoriteFolder, no createLink, no createMenuItem.

Bonus question On a brand-new v2.6.0 workspace, the favorites field is missing from the Query type entirely (Cannot query field "favorites" on type "Query"), while on an older v2.6.0 workspace (same version, upgraded from earlier) favorites is present. Standard data queries (tasks, notes, dashboards, workspaceMembers, etc.) all work fine on the new workspace — only favorites and favoriteFolders are absent from the schema. Is favorites only registered in the schema after some trigger, or is there a feature flag / env variable controlling it? Thank you!