Since she will be 18 after the cruise she will be 17 while cruising.
The nightclub is 18 to get in 21 to drink. They do check id. Too bad she will be a week shy of being able to get into the club.
The casino is also 18 and over.
The comedy show I have seen teens(16 & 17) in the theater. I don't recall anyone checking id at the theater entrance. Were they allowed in or did they sneak in...not sure.
The adult pool I've seen teens get told to leave and also teens that stay. If your daughter is with you and she looks at least 18 there is a chance nobody will ask her to leave.
Enjoy your cruise.