feat(oo): file deep links, login check, replace-in (fresh upload)

- link: print Products/Files/DocEditor.aspx?fileid=… deep links (title+url)
- lib: FileEditorURL/FolderURL helpers (+tests)
- users check: verify credentials (userName vs email) via authentication.json
- projects files replace-in FOLDER_ID FILE...: hard delete same stem|ext in a
  folder + fresh upload → single clean version (no version history)

cmd/oo/link.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	onlyoffice "github.com/eslider/go-onlyoffice"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(linkCmd())
+}
+
+func linkCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "link FILE_ID [FILE_ID...]",
+		Short: "Print OnlyOffice DocEditor deep links (Products/Files/DocEditor.aspx?fileid=…)",
+		Args:  cobra.MinimumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			c, err := newOO(cmd)
+			if err != nil {
+				return err
+			}
+			for _, id := range args {
+				printObject(map[string]any{
+					"fileid": id,
+					"title":  fileTitle(cmd, c, id),
+					"url":    c.FileEditorURL(id),
+				})
+			}
+			return nil
+		},
+	}
+}
+
+// fileTitle best-effort resolves a file title; never fails the command.
+func fileTitle(cmd *cobra.Command, c *onlyoffice.Client, id string) string {
+	f, err := c.GetFile(cmd.Context(), id)
+	if err != nil || f == nil || f.Title == nil {
+		return ""
+	}
+	return *f.Title
+}