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/duskdolphin/CMakeLists.txt

@@ -22,5 +22,6 @@ add_subdirectory(input)
 if(DUSK_NETWORK)
   add_subdirectory(network)
 endif()
+add_subdirectory(save)
 add_subdirectory(system)
 add_subdirectory(time)