compiler: a test program may hold a phase handler - the test runner called @rt_init whenever the program had systems, and a handler alone makes none (LLVM: use of undefined value '@rt_init'); it calls it only when it exists, as an entry program's main does; a ludic test case with a handler (added, not run); reseeded, bootstrap-cfree fixpoint holds

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

selfhost/backend/emit_decl.ludic

@@ -161,7 +161,7 @@ function emit_test_runner() -> void {
   emit(`{lrun0}:\n`)
   emit("  call void @L_init_runtime()\n")
   if has_ecs() { emit("  call void @L_grow(i32 1)\n") }
-  if has_ecs() { emit("  call void @rt_init()\n") }
+  if (find_fn("rt_init") != null) { emit("  call void " + fn_sym("rt_init") + "()\n") }   # as emit_main: a handler alone makes no rt_init
   emit("  call void @L_init_globals()\n")
   i = 0
   while i < len(g_tests) {