059 reject tilde after pipe forward

// ============================================================================
// Test 210_059: Reject tilde invocation after pipe-forward
// A pipe-forward (|>) chains into a continuation body, not a new flow.
// Writing `~call()` after `|>` is nonsensical — if you need to chain
// flows, use a branch binding and invoke from the continuation body.
// ============================================================================

~event greet { name: []const u8 }
| done []const u8

~proc greet {
    return .{ .done = "Hello!" };
}

~event farewell { name: []const u8 }
| done []const u8

~proc farewell {
    return .{ .done = "Goodbye!" };
}

// INVALID: ~ invocation after |> is not valid Koru
~greet(name: "World")
|>
~farewell(name: "World")