Auto-cancel stale option close limits after pending TTL.

Default 10m via OKX_OPTIONS_PENDING_TTL_SECONDS; show age/countdown in pending panel; monitor loop cancels sell closes.

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

lib/options/templates/options_panel.html

@@ -107,6 +107,7 @@
                                 <h4 class="opt-order-pending-title">委托</h4>
                                 <button type="button" class="btn-secondary" id="opt-pending-refresh">刷新</button>
                             </div>
+                            <p class="muted opt-pending-ttl-hint" id="opt-pending-ttl-hint">平仓限价超 10 分未成交将自动撤销</p>
                             <div id="opt-pending-list" class="opt-pending-list">
                                 <div class="muted opt-pending-empty">暂无未成交委托</div>
                             </div>
@@ -272,4 +273,4 @@
     </div>
 </div>
 <script src="/static/options_expiry_countdown.js?v=1"></script>
-<script src="/static/options_panel.js?v=30"></script>
+<script src="/static/options_panel.js?v=31"></script>