Prevent default when handling keyboard shortcuts

Without this, any default action would still happen. With Chrome on
Linux, that causes browser features to be triggered with our CTRL+J and
CTRL+K actions.

app/javascript/controllers/hotkey_controller.js

@@ -3,6 +3,7 @@ import { Controller } from "@hotwired/stimulus"
 export default class extends Controller {
   click(event) {
     if (this.#isClickable && !this.#shouldIgnore(event)) {
+      event.preventDefault()
       this.element.click()
     }
   }