chore(flow): expand host-return whitelist and add a DEBUG host bundle probe

- Rebuild the return-to-host whitelist from the CN/US top charts plus Apple
  system apps; drop the canOpenURL pre-check (LSApplicationQueriesSchemes
  is capped at 50) and let open() report failure.
- Never record an OSG bundle id as the host to return to.
- DEBUG only: probe the host bundle id through the keyboard arbiter
  callback and surface the log on a Home test card. Release builds keep
  the previous behaviour (no host identification).

OSGKeyboardShared/Utilities/HostBundleProbeLog.swift

@@ -0,0 +1,47 @@
+// HostBundleProbeLog.swift
+// OSGKeyboard · Shared
+//
+// 临时调试：键盘扩展把 arbiter 回调识别到的宿主 bundle ID 写进 App Group，
+// 主 App 首页读出来展示，用于真机验证 iOS 26.4+ 宿主识别方案。验证结束后删除。
+
+#if DEBUG
+import Foundation
+
+public enum HostBundleProbeLog {
+    public struct Entry: Codable, Equatable, Identifiable, Sendable {
+        public let id: UUID
+        public let date: Date
+        /// `appear`：键盘弹出（随后主动触发一次回调）；`arbiter`：系统回调。
+        public let event: String
+        /// 回调里读到的宿主 bundle ID；读不到时为 nil。
+        public let bundleId: String?
+        /// 回调参数的类名等辅助信息，方便字段失效时排查。
+        public let detail: String?
+    }
+
+    private static let key = "debug.hostBundleProbe.entries"
+    private static let limit = 40
+
+    /// 新记录插在最前面，只保留最近 `limit` 条。
+    public static func append(event: String, bundleId: String?, detail: String? = nil) {
+        guard let defaults = AppGroup.defaultsIfAvailable else { return }
+        let entry = Entry(id: UUID(), date: Date(), event: event, bundleId: bundleId, detail: detail)
+        let updated = Array(([entry] + entries()).prefix(limit))
+        guard let data = try? JSONEncoder().encode(updated) else { return }
+        defaults.set(data, forKey: key)
+    }
+
+    /// 按时间倒序返回。
+    public static func entries() -> [Entry] {
+        guard let data = AppGroup.defaultsIfAvailable?.data(forKey: key),
+              let decoded = try? JSONDecoder().decode([Entry].self, from: data) else {
+            return []
+        }
+        return decoded
+    }
+
+    public static func clear() {
+        AppGroup.defaultsIfAvailable?.removeObject(forKey: key)
+    }
+}
+#endif