The pure core of meditate: the breath engine, the orb scene, the half-block
renderers, the seasonal palette, and the title ramp — everything that is
free of I/O, clocks, and the terminal, so it compiles to both the native CLI
and wasm32-unknown-unknown for the web build.
What lives here is deterministic: the breath engine is driven by a session
clock the caller supplies on each tick, and capability/palette inputs are
passed in rather than detected. The native binding (std::env, the real
clock, the terminal) stays in the meditate crate.