Fix: edit comment button disappears when morphing the page

This also replaces the ad-hoc stimulus controller with the pure-css based
solution we recently added.

https://app.fizzy.do/5986089/cards/3243

app/javascript/controllers/created_by_current_user_controller.js

@@ -1,12 +0,0 @@
-import { Controller } from "@hotwired/stimulus"
-
-export default class extends Controller {
-  static targets = [ "creation" ]
-  static classes = [ "mine" ]
-
-  creationTargetConnected(element) {
-    if (element.dataset.creatorId == Current.user.id) {
-      element.classList.add(this.mineClass)
-    }
-  }
-}