Investigate how Kap currently exports GIFs and whether there is an existing API for adding overlays. The issue is a question with no further details; it would be useful to first clarify what kind of text watermark is desired (e.g., position, font, size). Check the Kap source code for GIF generation, likely using a library like gif.js or similar, and determine if adding text requires modifying that library or implementing a new feature.