082 effect branch resume value

// Test: effect-branch handler returns a resume value via bare-expression body.
//
// Producer declares `! ask []const u8 -> []const u8` (yield a question,
// resume with a reply) and uses the reply. Consumer's handler body is
// `! ask _ |> "Alice"` — the bare string literal IS the resume value.
//
// No `result` keyword, no `*` marker, no `;` terminator. Lars's destiny
// syntax (locked 2026-05-24): invocations always have parens, so anything
// at body position without trailing parens after the path is a Zig
// expression — terse and unambiguous.

~import "$std/io"

const std = @import("std");

~pub event prompt_user { question: []const u8 }
! ask []const u8 -> []const u8
| done []const u8

~proc prompt_user|zig {
    const reply = ask(question);
    return .{ .done = reply };
}

~prompt_user(question: "What's your name?")
! ask _ |> "Alice"
| done r |> std.io:print.blk {
    reply was: {{ r:s }}
}