Always show the on-screen keyboard on Steam Deck

Steam will eventually have smarts about whether a keyboard is active and will igore the request appropriately.

Fixes https://github.com/libsdl-org/SDL/issues/12595

(cherry picked from commit 03a53ce0d12163ee5f7986f9603d2ac010fba947)

src/video/SDL_video.c

@@ -5405,6 +5405,10 @@ bool SDL_GetTextInputMultiline(SDL_PropertiesID props)
 static bool AutoShowingScreenKeyboard(void)
 {
     const char *hint = SDL_GetHint(SDL_HINT_ENABLE_SCREEN_KEYBOARD);
+    if (!hint) {
+        // Steam will eventually have smarts about whether a keyboard is active, so always request the on-screen keyboard on Steam Deck
+        hint = SDL_GetHint("SteamDeck");
+    }
     if (((!hint || SDL_strcasecmp(hint, "auto") == 0) && !SDL_HasKeyboard()) ||
         SDL_GetStringBoolean(hint, false)) {
         return true;