Colored async / await (Vision Later — rejected by design)

Mako concurrency is colorless: crew / kick / join / channels / select.

The keywords async and await are rejected at lex time with a clear error pointing at crew/kick/channels. There is no dual-colored function coloring and no Future-returning async fn ABI.

This is intentional (see VISION.md / LANGUAGE.md): one calling convention, structured concurrency, no function-color split.

// Rejected:
// async fn f() { await g() }

// Idiomatic:
crew c {
    let j = c.kick(work())
    let v = j.join()
}