044 runtime run budget

// Test: std.runtime:run enforces budget via scope cost

~import "$std/runtime"
~import "$std/io"

~pub event expensive {}
| done {}

~proc expensive {
    return .{ .done = .{} };
}

~std.runtime:register(scope: "budget") {
    expensive(10)
}

const TEST_SOURCE = "~expensive()";

~std.runtime:run(source: TEST_SOURCE, scope: "budget", budget: 5)
| result _ |> std.io:print.ln("OK")
| exhausted _ |> std.io:print.ln("EXHAUSTED")
| parse_error _ |> std.io:print.ln("PARSE ERROR")
| validation_error _ |> std.io:print.ln("VALIDATION ERROR")
| event_denied _ |> std.io:print.ln("EVENT DENIED")
| dispatch_error _ |> std.io:print.ln("DISPATCH ERROR")
| scope_not_found _ |> std.io:print.ln("SCOPE NOT FOUND")