fix: clean up stale sorter entries and fix battery reactivity

ButtplugMessageSorter never deleted entries from _waitingMsgs after
resolving, causing unsolicited DeviceList messages (with reused Ids)
to be swallowed. Also fix battery level not updating in UI by accessing
the device through the Svelte $state proxy array.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/buttplug/src/utils/ButtplugMessageSorter.ts

@@ -49,6 +49,7 @@ export class ButtplugMessageSorter {
       let id = Messages.msgId(x);
       if (id !== Messages.SYSTEM_MESSAGE_ID && this._waitingMsgs.has(id)) {
         const [res, rej] = this._waitingMsgs.get(id)!;
+        this._waitingMsgs.delete(id);
         // If we've gotten back an error, reject the related promise using a
         // ButtplugException derived type.
         if (x.Error !== undefined) {