repl: fix screen refresh in multiline viewport overflow

When multiline REPL input exceeds the terminal height, navigating
the cursor would move the cursor position correctly but fail to
refresh the screen properly, leaving stale content visible.
This implements viewport-based rendering in kRefreshLine() that
displays only the visible portion of input centered around the
cursor position when content exceeds terminal height.

Author: Han5991

lib/internal/readline/interface.js

@@ -553,7 +553,7 @@ class Interface extends InterfaceConstructor {
         this[kWriteToOutput](`\n${kMultilinePrompt.description}` + lines[i]);
       }
 
-			this.prevRows = exceedsTerminal ? visibleCursorRow : cursorPos.rows;
+      this.prevRows = exceedsTerminal ? visibleCursorRow : cursorPos.rows;
     } else {
       // Write the prompt and the current buffer content.
       this[kWriteToOutput](line);