Add polished answer notifications (#1)

Sends a branded Resend email when a question receives its first answer, records accepted and failed sends, and adds collapsed answer editing with cancel behavior.

Co-authored-by: codegirl-007 <s.raide@gmail.com>

templates/question.html

@@ -23,12 +23,12 @@
     </div>
   </article>
   {{template "answer" .}}
-  {{if isAdmin .User}}
+  {{if and (isAdmin .User) (not .Answer)}}
     <form class="answer-form" method="post" action="/questions/{{.Question.ID}}/answer"
       hx-post="/questions/{{.Question.ID}}/answer" hx-target="#answer-block" hx-swap="outerHTML">
       <input type="hidden" name="_csrf" value="{{.CSRF}}">
-      <label for="answer-body">{{if .Answer}}Edit answer{{else}}Write the answer{{end}}</label>
-      <textarea id="answer-body" name="body" rows="8" required maxlength="12000">{{if .Answer}}{{.Answer.Body}}{{end}}</textarea>
+      <label for="answer-body">Write the answer</label>
+      <textarea id="answer-body" name="body" rows="8" required maxlength="12000"></textarea>
       <button type="submit" class="btn btn-primary">Save answer</button>
     </form>
   {{end}}