I'm not a security expert, but here are some of my thoughts.

First off, I'd call your building management and specifically ask what they are doing to address the problem. If there is a known issue and they aren't addressing it, you might have the ability to argue they have some responsibility here in the case of a break in. Not sure how far that would go, but if the problem is on-going and they're aware, what would a reasonable person do? Ignoring the problem isn't an answer.

Do you have a deadbolt, and if so, do you lock if often. Don't answer publicly - just lock it each time you leave if you aren't already. Do you have a chain for the door? If not, look at getting one - obviously only useful when you're at home, but might be worth it.

As for a deadbolt, they make strong ones that are less easy to tamper with - when I moved into my first Manhattan apartment, I put a new one on my door, saved the old one. When I moved out, just swapped them back out again and took it with me - nice to have.

As for the door jams and hinges, they likely come with tiny little screws - I replaced all mine with much larger screws (cheap at any home depot) and reinforced kick plates. Doesn't sound like these thieves are knocking down doors, but hey, better to be safe if they try it out.

I use Frontpoint security and would recommend it. It, like many security systems, has a mobile app that you can have alert you if a door opens when your alarm is set. I have all my doors set with the magnetic pieces that alert when they're opened, same with my windows. I arm the system from my phone whenever I leave and each night. Love the piece of mind and damn that thing is loud when you don't turn it off.

Additionally, teach your cat to bark. Loudly. Like a Mastiff. Seriously though, just incase, cat should have a microchip in him, if he should get out.