feat(crypto-tail): 价差策略监控页手动下单与 UI 优化

- 后端：手动下单 API，trigger_type 区分 AUTO/MANUAL，价格 4 位小数向上取整
- 前端：监控页手动买入 Up/Down 按钮、二次确认弹窗、策略信息移动端适配
- 下单价格最多 4 位小数；确认页方向仅显示 Up/Down；按钮文案改为「买入 Up/Down」

Made-with: Cursor

frontend/src/locales/en/common.json

@@ -1644,6 +1644,39 @@
       "switchToLatest": "Switch to Latest Period",
       "periodEnded": "Current period has ended",
       "newPeriodAvailable": "New period has started"
+    },
+    "manualOrder": {
+      "title": "Manual Order",
+      "buttonUp": "Buy Up",
+      "buttonDown": "Buy Down",
+      "confirmTitle": "Manual Order Confirmation",
+      "marketTitle": "Market Title",
+      "direction": "Direction",
+      "directionUp": "Up",
+      "directionDown": "Down",
+      "orderPrice": "Order Price",
+      "orderSize": "Order Size",
+      "totalAmount": "Total Amount",
+      "account": "Account",
+      "cancel": "Cancel",
+      "confirm": "Confirm Order",
+      "orderUnit": "USDC",
+      "sizeUnit": "shares",
+      "statusNotOrdered": "Not Ordered",
+      "statusOrdered": "This period has been ordered",
+      "statusOrderedAuto": "This period has been auto-ordered",
+      "statusOrderedManual": "This period has been manually ordered",
+      "errorInsufficientBalance": "Insufficient account balance, available: {balance} USDC",
+      "errorPriceOutOfRange": "Price must be between 0 and 1",
+      "errorMinSize": "Size cannot be less than 1 share",
+      "errorExceedsBalance": "Total amount exceeds available balance",
+      "errorPriceRequired": "Please enter order price",
+      "errorSizeRequired": "Please enter order size",
+      "success": "Manual order successful",
+      "failed": "Manual order failed: {{reason}}",
+      "errorSigning": "Signing failed: {reason}",
+      "errorNetwork": "Network error, please try again later",
+      "priceNotLoaded": "Price data not loaded"
     }
   }
 }