Wire the Max for Live device to the keyboard

Step 3 of the brief: the device now holds a ScaleLighting and pushes every
scale Live reports to the Apex 7, instead of only printing it.

The controller is created lazily and injected (start(max, { createLights })),
so the device stays testable with no Max and no hardware. Around the call:
lighting work is serialized on one queue so a burst of LOM changes cannot
interleave two POSTs, an unchanged scale is never re-sent, and a GameSense
that is missing or restarted is printed once rather than on every scale
change — the scale keeps being tracked so a later retry lands on the right one.

New messages: lights 0|1, retry, address <host:port>, shutdown. The patcher
gets boxes for them plus closebang -> shutdown, and the launcher blanks the
board on SIGTERM/SIGINT, so deleting the device hands lighting back to GG.

The test runner now supports async tests, since the lighting half is async.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

max/scale-device.js

@@ -26,5 +26,23 @@ if (!fs.existsSync(compiled)) {
     Max.POST_LEVELS.ERROR
   );
 } else {
-  require(compiled).start(Max);
+  const device = require(compiled).start(Max);
+
+  // Node for Max kills this process when the device is deleted or the Live set
+  // is closed. Blank the board on the way out so the Apex 7 goes back to its
+  // SteelSeries GG profile rather than sitting on the last scale. Best effort:
+  // if the signal never arrives, GameSense drops the effect ~15s after the
+  // heartbeat stops anyway. The patcher's `closebang` covers device deletion,
+  // which is the case Live does not signal.
+  let leaving = false;
+  const leave = () => {
+    if (leaving) return;
+    leaving = true;
+    device
+      .shutdown()
+      .catch(() => {})
+      .then(() => process.exit(0));
+  };
+  process.on('SIGTERM', leave);
+  process.on('SIGINT', leave);
 }