Add PSP/GameCube/Wii save-device availability checks

PSP checks memory-stick reachability via sceIoGetstat. GameCube gets two
devices (CARD_SLOTA/CARD_SLOTB), each mounted via CARD_Init/CARD_Mount and
checked for free space via CARD_GetDirectory/CARD_GetBlockCount. Wii picks
between three storage methods at compile time (DUSK_SAVE_WII_METHOD =
NAND/CARD/SD in wii.cmake, default NAND via ISFS) since real hardware
behavior for the default is unverified.

Also fixes two pre-existing bugs found while build/runtime-testing this
across PPSSPP and Dolphin: wrong libogc language macros in
systemGetLocaleDolphin, and a missing SYS_STDIO_Report(true) call that
silently swallowed all guest console output in Dolphin.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/duskpsp/save/savedeviceplatform.h

@@ -0,0 +1,16 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "savedevicepsp.h"
+
+#define SAVE_DEVICE_COUNT 1
+
+#define saveDevicePlatformInit saveDevicePSPInit
+#define saveDevicePlatformUpdate saveDevicePSPUpdate
+#define saveDeviceCheckAvailabilityPlatform saveDevicePSPCheckAvailability
+#define saveDevicePlatformDispose saveDevicePSPDispose