Day 1/90: Rust setup and cargo basics

90 Day Rust Challenge: Zero to Production

Today I wanted rust setup and cargo basics to feel like a real engineering decision, not a syntax demo. The useful shift was getting the Rust toolchain and Cargo workflow into a repeatable state from the first run.

The checks that mattered were toolchain installation and versions, cargo commands that form the daily loop, and crate layout that will survive later refactors.

The failure mode I was actively trying to avoid was treating the Cargo layout as disposable and rebuilding the same skeleton every week. I wanted rust setup and cargo basics to feel like something I could explain at a whiteboard or in a code review, not just something I recognized from docs.

That is the bar I want from this track: code that stays readable when requirements move, not just code that compiles today. I also want to keep tracing one concrete path through the code because that exposes weak assumptions faster than a larger demo.