addind more important kernel files and also fixing bugs

kernel/syscalls.c

@@ -1,5 +1,30 @@
 #include "syscalls.h"
+#include "scheduler.h"
+#include <stdarg.h>
 
-void syscall_handler() {
-    // Syscall handling code
+void syscall_handler(int code, va_list args) {
+    switch (code) {
+        case SYSCALL_INIT:
+            scheduler_init();
+            break;
+        case SYSCALL_SPAWN: {
+            void (*entry)(void) = va_arg(args, void (*)(void));
+            scheduler_add_task(entry);
+            break;
+        }
+        case SYSCALL_YIELD:
+            scheduler_yield();
+            break;
+        default:
+            // Unknown syscall
+            break;
+    }
+}
+
+void syscall(int code, ...)
+{
+    va_list args;
+    va_start(args, code);
+    syscall_handler(code, args);
+    va_end(args);
 }