The implementation that is currently visible in the GitHub commit history was done over about 3 days, yes. But that does not include the research, planning and architecture work that happened before I started committing the implementation.
I spent roughly 2 weeks researching the domain, figuring out the structure of the tool, planning the architecture and deciding how the different anatomical layers and interactions should work before the repo history you are looking at began.
I spent roughly 2 weeks researching the domain, figuring out the structure of the tool, planning the architecture and deciding how the different anatomical layers and interactions should work before the repo history you are looking at began.