feat: replace legacy vote buttons with AJAX submission and dynamic count updates

Replace static form-based vote buttons with a new VoteManager class that submits votes via fetch, returns JSON with net/up/down/current value, and updates vote count spans using data-vote-count attributes across all templates. Add JSONResponse endpoint in votes router for AJAX requests, switch VoteManager import from Http to Toast for error feedback, and refactor link_attachments to handle comma-separated UIDs.

devplacepy/templates/_comment_section.html

@@ -8,7 +8,7 @@
                 <input type="hidden" name="value" value="1">
                 <button type="submit" class="comment-vote-btn">+</button>
             </form>
-            <span class="comment-vote-count">{{ item.votes.up - item.votes.down }}</span>
+            <span class="comment-vote-count" data-vote-count="{{ item.comment['uid'] }}">{{ item.votes.up - item.votes.down }}</span>
             <form method="POST" action="/votes/comment/{{ item.comment['uid'] }}">
                 <input type="hidden" name="value" value="-1">
                 <button type="submit" class="comment-vote-btn">-</button>