044 transform arm real body legal

// The legal sibling of 220_043/220_045: under a transform head, an optional
// branch arm whose body does REAL work stays legal — `! tick _ |>` discards
// the payload but actually acts. Compile-only pin (no markers): the shape
// must not be refused.

~import std/io

~pub tor step {}
! ?tick i64
| ?done

~proc step|zig { return .{ .done = .{} }; }

~[comptime|transform]pub tor run { expr: Expression, item: *const std/compiler:Item, program: *const std/compiler:Program } -> SiteResult

~proc run|zig {
    const ast = @import("ast");
    const allocator = @import("std").heap.page_allocator;
    const flow = if (item.* == .flow) &item.flow else return .{};
    return .{ .replacement = ast.Item{ .inline_code = .{ .code = "// run ran", .location = flow.location, .module = allocator.dupe(u8, flow.module) catch return .{} } } };
}

~run()
! tick _ |> std/io:print.ln("tick")