v1.2.0: Add US overnight session real-time prices via Pyth/TradingView API

- Add PythService.swift: fetch overnight prices from us-overnight-stock-api.vercel.app
- Restore "夜盘" session in usMarketSession() (ET 20:00-04:00)
- Parallel fetch Sina + Pyth during overnight, merge once to avoid UI flicker
- Clear stale after-hours extendedPrice before applying overnight data

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

StockMonitor/Services/PythService.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+/// 美股夜盘 (ET 20:00–04:00) 实时报价
+/// 数据源：Pyth Network / TradingView BOATS（via Vercel API）
+final class PythService {
+
+    private static let baseURL = "https://us-overnight-stock-api.vercel.app/api"
+
+    /// 批量获取美股夜盘价格，返回 [stockCode: overnightPrice]
+    /// stockCodes 格式如 ["usr_aapl", "usr_tsla"]
+    static func fetchOvernightPrices(codes: [String]) async -> [String: Double] {
+        var result: [String: Double] = [:]
+
+        await withTaskGroup(of: (String, Double?).self) { group in
+            for code in codes {
+                group.addTask {
+                    let symbol = code.replacingOccurrences(of: "usr_", with: "").uppercased()
+                    let price = await fetchPrice(symbol: symbol)
+                    return (code, price)
+                }
+            }
+            for await (code, price) in group {
+                if let p = price {
+                    result[code] = p
+                }
+            }
+        }
+        return result
+    }
+
+    /// 获取单只股票夜盘价格
+    private static func fetchPrice(symbol: String) async -> Double? {
+        guard let url = URL(string: "\(baseURL)?symbol=\(symbol)&session=overnight") else { return nil }
+        guard let (data, _) = try? await URLSession.shared.data(from: url),
+              let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
+              let price = json["price"] as? Double,
+              price > 0 else { return nil }
+        return price
+    }
+}

StockMonitor/State/AppState.swift

@@ -161,12 +161,29 @@ final class AppState: ObservableObject {
             let all       = stocks.map(\.id)
             let sinaCodes = all.filter { !$0.hasPrefix("hk") }
             let hkCodes   = all.filter {  $0.hasPrefix("hk") }
-            async let sinaResult  = DataService.fetchSinaQuotes(codes: sinaCodes)
-            async let hkResult    = DataService.fetchTencentHKQuotes(codes: hkCodes)
-            async let ratesResult = CurrencyService.fetchRates()
+
+            let isOvernight = Self.usMarketSession() == "夜盘"
+            let usCodes = isOvernight ? all.filter { $0.hasPrefix("usr_") } : []
+
+            // 所有数据源并行请求
+            async let sinaResult      = DataService.fetchSinaQuotes(codes: sinaCodes)
+            async let hkResult        = DataService.fetchTencentHKQuotes(codes: hkCodes)
+            async let ratesResult     = CurrencyService.fetchRates()
+            async let overnightResult = PythService.fetchOvernightPrices(codes: usCodes)
+
             let (s, h) = try await (sinaResult, hkResult)
-            let rates  = await ratesResult
-            quotes.merge(s) { $1 }
+            let rates     = await ratesResult
+            let overnight = await overnightResult
+
+            // 夜盘时段：清除新浪的盘后旧价格，用夜盘实时价替换
+            var merged = s
+            if isOvernight {
+                for key in merged.keys where key.hasPrefix("usr_") {
+                    merged[key]?.extendedPrice = overnight[key]
+                }
+            }
+
+            quotes.merge(merged) { $1 }
             quotes.merge(h) { $1 }
             exchangeRates  = rates
             lastUpdateTime = Date()
@@ -261,12 +278,24 @@ final class AppState: ObservableObject {
         let comps = cal.dateComponents([.weekday, .hour, .minute], from: now)
         let weekday = comps.weekday ?? 1
         let minutes = (comps.hour ?? 0) * 60 + (comps.minute ?? 0)
-        guard weekday >= 2, weekday <= 6 else { return nil }
         switch minutes {
-        case 240..<570:  return "盘前"   // ET 04:00–09:30
-        case 570..<960:  return "盘中"   // ET 09:30–16:00
-        case 960..<1200: return "盘后"   // ET 16:00–20:00
-        default:         return nil      // 夜盘无数据源，不显示
+        case 0..<240:
+            guard weekday >= 3, weekday <= 7 else { return nil }
+            return "夜盘"    // ET 00:00–04:00（跨日，周二夜~周六凌晨）
+        case 240..<570:
+            guard weekday >= 2, weekday <= 6 else { return nil }
+            return "盘前"    // ET 04:00–09:30
+        case 570..<960:
+            guard weekday >= 2, weekday <= 6 else { return nil }
+            return "盘中"    // ET 09:30–16:00
+        case 960..<1200:
+            guard weekday >= 2, weekday <= 6 else { return nil }
+            return "盘后"    // ET 16:00–20:00
+        case 1200..<1440:
+            guard weekday >= 2, weekday <= 6 else { return nil }
+            return "夜盘"    // ET 20:00–24:00
+        default:
+            return nil
         }
     }
 }