port: EterLib/Input over host key events (DirectInput polling adapted)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/port/port_input_test.cpp

@@ -0,0 +1,41 @@
+// 40250 CInputKeyboard with host key events in place of DirectInput polling (platform/EterLib/Input.cpp).
+#include "EterLib/StdAfx.h"
+#include "EterLib/Input.h"
+
+#include <cstdio>
+
+namespace {
+struct Keyboard : CInputKeyboard
+{
+	int downs = 0, ups = 0;
+	void OnKeyDown(int) override { ++downs; }
+	void OnKeyUp(int) override { ++ups; }
+	char Diks(int i) const { return ms_diks[i]; }
+};
+}
+
+int main()
+{
+	int failures = 0;
+	auto check = [&failures](bool ok, const char *name) {
+		if (!ok) {
+			std::fprintf(stderr, "FAIL %s\n", name);
+			++failures;
+		}
+	};
+
+	Keyboard kb;
+	check(kb.InitializeKeyboard(NULL), "InitializeKeyboard");
+	kb.KeyDown(DIK_LCONTROL);
+	check(kb.IsPressed(DIK_LCONTROL) && (kb.Diks(DIK_LCONTROL) & 0x80), "KeyDown records the key and the device byte");
+	kb.UpdateKeyboard();
+	check(kb.IsPressed(DIK_LCONTROL) && kb.downs == 0 && kb.ups == 0, "UpdateKeyboard neither polls nor dispatches");
+	kb.KeyUp(DIK_LCONTROL);
+	check(!kb.IsPressed(DIK_LCONTROL) && kb.Diks(DIK_LCONTROL) == 0, "KeyUp");
+	kb.KeyDown(-1);
+	kb.KeyDown(256);
+	kb.KeyDown(DIK_A);
+	Keyboard other; // the state is static: a new keyboard resets it, as in 40250
+	check(!kb.IsPressed(DIK_A), "constructor ResetKeyboard clears the shared state");
+	return failures ? 1 : 0;
+}