Fix double POST on open position in embed shell mode.

Embed capture-phase form handler and allowManualOrderSubmit both submitted /add_order; skip custom forms and use a single fetch reload path.

Co-authored-by: Cursor <cursoragent@cursor.com>

embed_templates/embed_shell.html

@@ -115,6 +115,6 @@
 <script src="/static/manual_order_rr_preview.js?v=3"></script>
 <script src="/static/key_monitor_form.js?v=1"></script>
 {% include 'embed_boot_scripts.html' %}
-<script src="/static/instance_embed.js?v=3"></script>
+<script src="/static/instance_embed.js?v=4"></script>
 </body>
 </html>