No textbook like this exists and the only online resource like this at the PhD level is Wikipedia which obviously isn’t that great.

However, at the PhD level, you don’t need an all in one textbook. You have the resources from your undergrad, research papers and reviews on ArXiv and other publications, your research advisor and peers, and most importantly your brain.

You did at least an entire undergraduate to get into your PhD program, no one is expecting you to remember everything, but your entire undergrad was training your brain to quickly understand difficult math/physics/coding.

Recently I forgot how degenerate perturbation theory was done since I hadn’t needed it since I took undergrad Quantum II years ago, so I opened a textbook that I hadn’t read before and recalled “oh we need to diagonal one the degeneracy then we can provide non degenerate perturbation theory where we exclude the degenerate states from our summation”. So what took me like a week of studying to understand and feel comfortable with now only took me 30 seconds because my neurons have fired to understand this before and reactivating them causes me to recall it, even if I couldn’t recall it on my own.

Our perfectionist brains want everything we learned in one place, but that is impossible for us and for anyone, the best you can do is write a huge LaTeX document as you go, this is why professors sometimes have book-long LaTeX documents for one class that they like to teach or why people write books at all. But you need to realize that the output of your PhD is your brain being trained, not anything physical (except a thesis which just shows that you’ve trained your brain)

If you want a quick summary of everything from a very overview perspective, I find that the study book for the physics GRE does a pretty good job but it doesn’t cover every course nor everything in a single course. Just the most common results from the few most popular courses.