fix(render3d): a rim from outline_model goes out when the caller stops asking

The queue was only emptied by the next outline_model call, so the last highlighted tree kept
its rim after the player looked away. r3d_frame now calls outline_frame, which drops a batch
the previous frame closed and nobody reopened.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/ludic.render3d/render.ludic

@@ -124,6 +124,7 @@ function r3d_resize() -> void {
   print(`r3d: resized to {gl_w}x{gl_h}`)
 }
 function r3d_frame(time: int) -> void {
+  outline_frame()
   if not r3d_ready { return }
   if gl_resize_check() { r3d_resize() }
   # R3D_RESIZE_AT=<frame>: rebuild every screen-sized buffer mid-run, as a window resize