046 metatype enum helpers

// Test 310_046: Metatype enum helper functions
// Verify that Transition metatype with enum-based fields compiles and works
// The taps namespace should have eventToString() and branchToString() helpers

~import std/taps

~event process { value: i32 }
| ok i32
| error []const u8

~event logger { msg: []const u8 }

~[pure]proc process|zig {
    if (value > 0) {
        return .{ .ok = value };
    }
    return .{ .error = "negative" };
}

~[pure]proc logger|zig {
}

// Tap that captures Transition (enum-based metatype)
// The compiler should emit eventToString() and branchToString() helpers in taps namespace
~tap(process -> *)
| Transition _ |> logger(msg: "transition")

~process(value: 5)
| ok _ |> _
| error _ |> _

~process(value: -1)
| ok _ |> _
| error _ |> _