191 zig only proc js build refuses

// PINS: a Zig-only proc on a --lang=js build must REFUSE CLEANLY — a
// located diagnostic naming the code, never a panic.
//
// The old surface was std.debug.panic("js_emitter.emit failed: {s}") at
// koru_std/compiler.kz emission: every program whose event has no JS
// implementation (a zig-only proc, an unmodelled construct) died with
// SIGABRT + a raw backtrace that read as a compiler bug and buried the
// reason. The [js_emitter] log line ABOVE the panic named the event; the
// panic threw that away.
//
// JS_REFUSES asserts the refusal is the clean diagnostic — the
// `error[KORU047]:` line that only exists after the conversion. Under the
// old panic the js build printed the log line but no error[KORU0xx] line,
// so this pin reds there and greens here. The bench's mock-gate hit this
// shape (event-name with a zig-only proc) while rebuilding; the zig build
// was separately poisoned by a js-lang backend in the content cache.
const std = @import("std");

~pub tor ping { msg: string }
~proc ping|zig { std.debug.print("pong {s}\n", .{msg}); }
~ping(msg: "hello")