fix(hub): merge mark price from Flask snapshot and fix board refresh

Sync hub positions with instance price_snapshot (order_prices and position_marks).
Fix monitor board UI when hub restarts (version rewind) and queue snapshot fetches.
Expose board aggregate status on /api/ping for diagnostics.

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

crypto_monitor_okx/app.py

@@ -6005,10 +6005,18 @@ def api_price_snapshot():
         )
         order_prices.append(payload)
 
+    from hub_position_metrics import build_position_marks_list
+
+    position_marks = build_position_marks_list(
+        all_swap_positions,
+        format_mark_display=lambda sym, px: format_price_for_symbol(sym, px),
+    )
+
     return jsonify({
         "updated_at": app_now_str(),
         "key_prices": key_prices,
         "order_prices": order_prices,
+        "position_marks": position_marks,
         "positions_raw_count": len(all_swap_positions),
     })