Add Basecamp-style boosts

app/javascript/controllers/reaction_emoji_controller.js

@@ -0,0 +1,11 @@
+import { Controller } from "@hotwired/stimulus"
+
+export default class extends Controller {
+  static targets = [ "input" ]
+
+  insertEmoji(event) {
+    const emojiChar = event.target.getAttribute("data-emoji")
+    const value = this.inputTarget.value
+    this.inputTarget.value = `${value}${emojiChar}`
+  }
+}