enable vsync by default for sdl3 backend, cleanup headers:

src/pxl8.c

@@ -2,20 +2,16 @@
 #define PXL8_COPYRIGHT "Copyright (c) 2024-2025 pxl8.org"
 #define PXL8_VERSION "0.1.0"
 
-#include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
-#include <linenoise.h>
-
 #include "pxl8_cart.h"
 #include "pxl8_game.h"
 #include "pxl8_hal.h"
 #include "pxl8_macros.h"
 #include "pxl8_script.h"
-#include "pxl8_sdl3.h"
 #include "pxl8_types.h"
 #include "pxl8_ui.h"
 

src/pxl8_io.c

@@ -1,10 +1,13 @@
-#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "pxl8_io.h"
 #include "pxl8_types.h"
 
+static inline char pxl8_to_lower(char c) {
+    return (c >= 'A' && c <= 'Z') ? c + 32 : c;
+}
+
 pxl8_result pxl8_io_read_file(const char* path, char** content, size_t* size) {
     if (!path || !content || !size) return PXL8_ERROR_NULL_POINTER;
     
@@ -121,7 +124,7 @@ static i32 pxl8_key_code(const char* key_name) {
     char lower_name[64];
     size_t i;
     for (i = 0; i < sizeof(lower_name) - 1 && key_name[i]; i++) {
-        lower_name[i] = (char)tolower((unsigned char)key_name[i]);
+        lower_name[i] = pxl8_to_lower(key_name[i]);
     }
     lower_name[i] = '\0';
 

src/pxl8_sdl3.c

@@ -57,6 +57,10 @@ static void* sdl3_create(pxl8_color_mode mode, pxl8_resolution resolution,
         return NULL;
     }
 
+    if (!SDL_SetRenderVSync(ctx->renderer, 1)) {
+        pxl8_error("Failed to enable vsync: %s", SDL_GetError());
+    }
+
     SDL_SetRenderLogicalPresentation(ctx->renderer, fb_w, fb_h,
                                      SDL_LOGICAL_PRESENTATION_INTEGER_SCALE);