feat: 盈亏比与亏损额度展示，市价FAK报单，修复止盈止损保存失败

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

static/css/trade.css

@@ -36,6 +36,7 @@
 .trade-action-row .btn-open.btn-session-off{background:var(--text-muted);border-color:var(--text-muted)}
 .trailing-be-toggle{display:flex;align-items:center;gap:.4rem;font-size:.78rem;color:var(--text-label);margin-bottom:.45rem;cursor:pointer;user-select:none}
 .trailing-be-toggle input{width:auto;margin:0}
+.trade-rr-hint{font-size:.78rem;color:var(--text-accent);margin:0}
 .session-hint{font-size:.72rem;margin:.35rem 0 0;text-align:center}
 .trade-order-msg{font-size:.82rem;text-align:center;margin:0;padding:.35rem}
 .trade-order-msg.ok{color:var(--profit)}