[fix] restore Windows remote keyboard shortcuts and input recovery

apps/desktop/src/platform/common/input/keyboard_state.h

@@ -0,0 +1,71 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-10-09
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _KEYBOARD_STATE_H_
+#define _KEYBOARD_STATE_H_
+
+#include <algorithm>
+#include <cstdint>
+#include <map>
+#include <vector>
+
+namespace crossdesk {
+
+struct KeyboardKey {
+  int key_code = 0;
+  uint32_t scan_code = 0;
+  bool extended = false;
+};
+
+using PressedKeys = std::map<int, KeyboardKey>;
+
+struct KeyboardInput {
+  int key_code = 0;
+  bool is_down = false;
+  uint32_t scan_code = 0;
+  bool extended = false;
+};
+
+inline bool IsKeyboardModifier(int key_code) {
+  return (key_code >= 0x10 && key_code <= 0x12) ||
+         (key_code >= 0xA0 && key_code <= 0xA5) ||
+         key_code == 0x5B || key_code == 0x5C;
+}
+
+// Reconcile state after capture overflow without replaying discarded shortcuts.
+// Keep keys that are still held, release stale keys, then restore modifiers
+// before ordinary keys. Metadata matters for Enter/numpad Enter, etc.
+inline std::vector<KeyboardInput> ReconcileKeyboardState(
+    const PressedKeys& current, const PressedKeys& desired) {
+  const auto same_key = [](const KeyboardKey& a, const KeyboardKey& b) {
+    return a.scan_code == b.scan_code && a.extended == b.extended;
+  };
+  std::vector<KeyboardInput> result;
+  for (const auto& [code, key] : current) {
+    const auto it = desired.find(code);
+    if (it == desired.end() || !same_key(key, it->second))
+      result.push_back({code, false, key.scan_code, key.extended});
+  }
+  // Release ordinary keys before modifiers as well.
+  std::stable_partition(result.begin(), result.end(), [](const auto& key) {
+    return !IsKeyboardModifier(key.key_code);
+  });
+  const auto releases = result.size();
+  for (const auto& [code, key] : desired) {
+    const auto it = current.find(code);
+    if (it == current.end() || !same_key(key, it->second))
+      result.push_back({code, true, key.scan_code, key.extended});
+  }
+  std::stable_partition(result.begin() + releases, result.end(),
+                        [](const auto& key) {
+                          return IsKeyboardModifier(key.key_code);
+                        });
+  return result;
+}
+
+}  // namespace crossdesk
+
+#endif