feat: attach screenshots to issue comments (#467)

frontend/index.html

@@ -297,6 +297,15 @@
       <textarea id="issue-comment" maxlength="10000" placeholder="Write a comment"></textarea>
       <div class="mention-options" id="issue-comment-mentions" role="listbox" aria-label="Teammates" hidden></div>
       <div class="mention-status small" id="issue-comment-mention-status" aria-live="polite"></div>
+      <div class="issue-attachment-controls">
+        <input class="visually-hidden" id="issue-attachment" type="file" accept="image/png,image/jpeg,image/webp" />
+        <label class="issue-attachment-trigger" for="issue-attachment">Attach screenshot</label>
+      </div>
+      <div class="issue-attachment-preview" id="issue-attachment-preview" hidden>
+        <img id="issue-attachment-image" alt="Selected screenshot preview" />
+        <span class="small" id="issue-attachment-meta"></span>
+        <button id="remove-issue-attachment" type="button">Remove screenshot</button>
+      </div>
       <div class="comment-actions">
         <button id="send-issue-comment" type="button">Post comment</button>
         <button id="send-issue-comment-next" type="button" hidden>Comment &amp; next</button>
@@ -660,6 +669,7 @@
 <script src="static/later-picker.js"></script>
 <script src="static/pick-work.js"></script>
 <script src="static/conversation.js"></script>
+<script src="static/issue-attachment.js"></script>
 <script src="static/issue-sheet.js"></script>
 <script src="static/create-issue-sheet.js"></script>
 <script src="static/create-and-start.js"></script>