feat: implement montauk::service_log & add support to system services

programs/src/printd/main.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <montauk/syscall.h>
+#include <montauk/service_log.h>
 #include <print/print.hpp>
 #include "test_page_jpeg.hpp"
 
@@ -64,12 +65,15 @@ static void write_daemon_state(const char* phase, const char* subject = nullptr,
 }
 
 static void log_msg(const char* fmt, ...) {
+    char body[768];
     va_list ap;
     va_start(ap, fmt);
-    printf("[printd] ");
-    vprintf(fmt, ap);
-    printf("\n");
+    vsnprintf(body, sizeof(body), fmt, ap);
     va_end(ap);
+
+    char line[800];
+    snprintf(line, sizeof(line), "[printd] %s", body);
+    montauk::service_log(line);
 }
 
 static void set_job_state(JobMeta* job, const char* state, const char* message) {