127 effect arm discharge emits correct zig

// Arm sibling of 400_106: a resume ARM may carry a discharge phantom
// (`| granted *Resource<!active>`), and the phantom must be stripped from the
// emitted Zig — the synthesized resume union field is `granted: *Resource`,
// NOT `granted: *Resource<!active>`. Arm-ISSUE (`<active!>`) is the forbidden
// direction, pinned in 400_124.
const std = @import("std");
const Resource = struct { id: usize };
var global_r = Resource{ .id = 99 };

~pub event borrow { n: usize }
! lend usize
    | granted *Resource<!active>
    | denied
| done usize
~proc borrow|zig {
    const r = lend(n);
    switch (r) {
        .granted => |g| std.debug.print("got {}\n", .{g.id}),
        .denied => std.debug.print("denied\n", .{}),
    }
    return .{ .done = n };
}

~borrow(n: 3)
! lend _ => granted &global_r
| done _ |> _