002 match nested in for

// Nested match — `std/regex:match` under `for`'s `! each` handler. The
// match event declares its user-surface contract (`| \`*\` *` raw-name
// class + `| ?no-match` void), so nested validation passes by DEFAULT
// checking, no transform-trust exemption: the qualified invocation resolves
// to std.regex's event, pattern branches resolve to the `*` class (payload
// → bind or discard), no-match resolves exact (void → bindingless).
//
// The shape matters: it is the regex benchmark's hot loop
// (benchmarks/workloads/regex_match/koru/input.kz).
import std/regex
import std/io

for(0..3)
! each _ |> std/regex:match("foo@bar")
            | `[a-z]+@[a-z]+` _ |> std/io:print.ln("hit")
            | no-match |> std/io:print.ln("miss")