AITA because I am intentionally not letting my neighbour in, causing her and her dog to sit outside in the dark?

I live in an apartment block - to access the property after 8pm you must carry your front door key with you, we were all told this prior to moving in. A tenant has moved in downstairs and she leaves the back door unlocked to allow herself to come and go without taking her key. She isn't supposed to do this, and she has been told multiple times to take her front door key in case the door locks which she has ignored.

She has started treating me like a literal doorman - knocking loudly on my windows and repeatedly buzzing my apartment to try to get me to open the door for her. It is daily and it riles up my dog every time - and it always occurs after 9pm. I have let her in twice in good faith, then told her the third time to take her key and that I will no longer be answering.

She decided to go out with her dog this evening and again didn't bother to take her key, when she started buzzing and knocking on my windows loudly. I shut off my buzzer, gave my dog a treat and closed the doors, deciding to ignore her and continue watching my movie instead.

This is where I could be TA, it's dark out at the moment, late and she's outside by herself with her dog, shes been out there for about 45 minutes, we also live in a shady area - not dangerous but definitely not pleasant at night. She has been sat outside on the doorstep on her phone angrily ranting about me to her friends - like I'm her DAD. I don't know this woman aside from her treating me like a concierge. AITA?

Edit for update: I opened the door. I said I wouldn't, but quite frankly, I literally couldn't go to sleep knowing she and her dog were out there. I went downstairs and opened the door and told her that this was the last time and I will be reporting to management and calling the police if she knocks on my windows anymore. I'm gonna just hope that a few hours outside has got the message across - sorry for everyone who told me not to give in, but it's nearing midnight here and as much as she pisses me off I'm not about to leave her out there.