105 effect payload in obligation transfer

// REQUIREMENT (effect-branch obligations, payload-IN transfer — the symmetry):
// The proc ISSUES a per-firing obligation and transfers it INTO the handler via
// the `! make` payload (`*Resource<active!>`). The handler RECEIVES the live
// obligation and must discharge it within the firing (no resume to carry it
// out). Producer allocates, consumer consumes — per firing, balanced.
~import std/build
~std/build:requires { exe.linkLibC(); }
const std = @import("std");
const Resource = struct { id: usize };
const allocator = std.heap.c_allocator;

~event destroy { r: *Resource<!active> }
~proc destroy|zig { std.debug.print("freed {}\n", .{r.id}); allocator.destroy(r); }

~pub event gen { n: usize }
! make *Resource<active!>
| done usize
~proc gen|zig {
    for (0..n) |i| {
        const r = allocator.create(Resource) catch unreachable;
        r.* = Resource{ .id = i };
        make(r);
    }
    return .{ .done = n };
}

~gen(n: 3)
! make r |> destroy(r)
| done _ |> _