😀

1) “What I just said might sound like a pun, but I wasn’t trying to make one.”

2) “I am deliberately making a pun and saying ‘no pun intended’ to sarcastically call attention to it.”

You know your co-worker better than I do, obviously, so you’ll be better able to tell which is the case.

My guess is that it’s #1 above. In terms of definitions, “I’ll do ya proud” could be interpreted as she’s going to do something that you can be proud of, OR as slang that she’s going to have sex with you and you can be proud of that. I would guess that she’s going to do something that you can be proud of, she typed “I’ll do ya proud,” she realized what it sounded like, and she added “no pun intended” to show that she didn’t mean to sound like she was coming on to you. So it’s probably nothing to worry about, and there’s no need to respond to her unintentional wordplay.