IMHO, this is a question about how to deal with Asperger's, which I will explain...
First, you said:
Also might be relevant: she's mentioned having ADHD, and maybe autism (not 100% sure if I'm remembering that correctly).
...yes, it is very relevant. Asperger is along that same ADHD-Autism spectrum. The moment you described the loud "clap" and outburst, I thought of this.
I have a lot of experience dealing with friends, students, and coworkers who have Asperger and I recognize two things right away: Asperger and Leveler Mode.
Based on my experience, you must use the most direct communication possible, genuinely caring for the person, and explaining how you feel. You must assume that your coworker has no idea that you feel the way you do.
Consider a few ideas and quotes from these two important topics:
1. Asperger syndrome (wiki)
About Asperger (or something similar)
Some people need to learn social skills much the way one learns a golf swing. Your coworker probably never considered that clapping that loud or speaking that loud is alarming to others. She may not want to be told either, but if you can get through to her, probably through kindness and explanation, she may be glad you did.
Advice from a person with Asperger's to other people with Asperger's:
Instead of memorizing specific responses to specific situations, learn to understand the reasons behind a social situation. Train yourself to think through what other people expect from a situation, and ponder how you can help meet the expectations of others and make the interaction more positive.
— How To Learn Social Skills With Asperger’s Syndrome
The above quote is not intended for you, but for people like your coworker trying to understand you. By understanding this quote, you may understand how your coworker thinks.
In fact, just tonight, I came off of a four hour conversation with a friend who shows some Asperger traits. At one point, he told me that I have no friends. Rather than being offended, I recognized the comment as "socially challenged" (in the Asperger flavor of that) and responded in Leveler Mode:
Are you aware that today you are "Asper-splaining" a little more than usual?
(We have the rapport where we can talk openly about Asperger with each other. In fact, most people with Asperger's traits somewhat like the label, in my experience.)
All of the negativity dropped and he shifted right into what was really on his mind: artwork. I simply said the most direct and literal version of what was on my mind. That is "Leveler Mode"...
2. Satir's five modes (particularly 'Leveler')
Asperger and Leveler Mode can have an overlap: People with Autism Spectrum Disorder Take Things Literally. So, it may seem off topic, but Asperger and Leveler Mode are very related! If you think someone shows Asperger traits, interacting in Leveler Mode just might do the trick.
About "Leveler Mode"
This "mode" is when someone speaks very, very literally. It can be off-putting, but not meant to be affrontive. The best way to deal with a "Leveler" is to just "level back", speaking literally and directly in return. In general, training yourself to not fear raised voices is the first step.
The Leveler response is the most effective behavior for solving problems creatively. Their body posture communicates the idea that they are being to true to what they think. They come across as ‘on the level’, centered and factual.
— 5 Satir Categories for Understanding Communication Styles
The Leveler does just what Dr. Satir’s term implies; this person levels with you. When the Leveler is genuine, there is nothing simpler to deal with — just level back.
— Verbal Self-Defense: Chapter 2 – The Five Satir Modes
Next time she shouts like that, be happy, confident, not the least "careful" in your approach, and say this with a smile in your voice:
"Alice, I'm glad you are getting things done, but my ears are ringing, literally. Could you warm up your voice or something before you celebrate in the future. Or, at least invite me to the party and tell me what is so interesting."
That is literal (Leveler Mode) and helps explain the social situation to your coworker. It is also friendly (inviting and hoping for more interaction) and a little comical (good for diplomacy).
Another approach, maybe a little more bold...
Alice, might you have Asperger's or something similar? (if so...) Do you mind if I point it out when you do something that is really socially strange, or at least if it is troublesome for me?
...You might not even need to say why.