Our '14 CX-5 just had some fender damage fixed, but have just discovered damage to the leading edge of the hood that cracked and knocked off a little bit of paint. Does Mazda galvanize or somehow treat the metal to prevent the exposed area from rusting?

 

Anything can rust if you live with tons of road salt and the vehicle does not get washed enough or has paint damage like yours but your car is getting old at being a 2014 so depending....
on your climate - you can only do so much in the end, Winter is tough on cars but If I recall our hoods are steel. They are pretty heavy compared to other makes to me.

 

Most manufacturers use electroplate galvanizing now and some use other special primers.
As Subperson said, Galvanized steel will still rust it just takes far longer than ungalvanized steel.
If the galvanization has been dented, scratched or otherwise affected it will rust much more quickly.
It would be best to correctly repair any hood damage that you have to help prevent rusting.

 

To add most primers are not sealers so keep that in mind when you are DIY the painting repair!