Function apply_workspace_edit 

pub fn apply_workspace_edit(
    edit: &Value,
    project_root: &Path,
) -> Result<Vec<PathBuf>>

Apply a JSON WorkspaceEdit to files on disk atomically.

Handles both changes (old form: {uri: [TextEdit]}) and documentChanges (new form with TextDocumentEdit).

Returns the list of absolute paths that were modified.

Errors

Returns an error if any file cannot be read or written.