feat: add screenshot app

programs/lib/libjpegwrite/stb_image_write_impl.c

@@ -0,0 +1,23 @@
+/*
+ * stb_image_write_impl.c
+ * Single compilation unit for stb_image_write JPEG encoder on MontaukOS
+ * Copyright (c) 2026 Daniel Hammer
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+/* Only enable JPEG writing. */
+#define STBI_WRITE_NO_STDIO
+
+/* Route allocations through libc (which uses MontaukOS heap). */
+#define STBIW_MALLOC(sz)         malloc(sz)
+#define STBIW_FREE(p)            free(p)
+#define STBIW_REALLOC(p, newsz)  realloc(p, newsz)
+#define STBIW_MEMMOVE(d, s, n)   memmove(d, s, n)
+
+#define STBIW_ASSERT(x)  ((void)(x))
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include <gui/stb_image_write.h>