048 reject for terminal each

// Test 320_048: MUST_ERROR — reject the pre-migration `for(...) | each |>` form.
//
// `for`'s `each` is an EFFECT branch (declared `! each *` in std/control), so
// handling it with a terminal `|` continuation is illegal. The compiler must
// reject it with a clear KORU025 error whose hint points the user at the fix
// (`! each`). This pins the rejection of the old terminal-each syntax after the
// for→effect-branch migration; the legal form lives next door in 320_040
// (`! each _ |> _`). Lars's requirement: the invalid form must fail with a
// SENSIBLE message, not just fail — hence the CONTAINS assertions on the hint.

~import std/control

const std = @import("std");

~tor start {}

~proc start|zig {
}

~start() |> for(&[_]i32{1, 2, 3})
| each _ |> _
| done |> _