Test Vi mode dfX

Tests d25965afba (Vi mode: hack in support for df and friends,
2026-02-06).

tests/pexpects/vi-key-bindings.py

@@ -28,3 +28,10 @@ sleep(1)
 send("li123")
 sendline("")
 expect_re(r"\bsuggest-thi123s\b")
+
+send("echo hello world")
+send("\033")
+sleep(1)
+send("0wdfw")
+sendline("")
+expect_re(r"\borld\b")