Fix VRAM leak in tiler fallback in video VAEs (#13073)

* sd: soft_empty_cache on tiler fallback

This doesnt cost a lot and creates the expected VRAM reduction in
resource monitors when you fallback to tiler.

* wan: vae: Don't recursion in local fns (move run_up)

Moved Decoder3d’s recursive run_up out of forward into a class
method to avoid nested closure self-reference cycles. This avoids
cyclic garbage that delays garbage of tensors which in turn delays
VRAM release before tiled fallback.

* ltx: vae: Don't recursion in local fns (move run_up)

Mov the recursive run_up out of forward into a class
method to avoid nested closure self-reference cycles. This avoids
cyclic garbage that delays garbage of tensors which in turn delays
VRAM release before tiled fallback.

comfy/sd.py

@@ -978,6 +978,7 @@ class VAE:
             do_tile = True
 
         if do_tile:
+            comfy.model_management.soft_empty_cache()
             dims = samples_in.ndim - 2
             if dims == 1 or self.extra_1d_channel is not None:
                 pixel_samples = self.decode_tiled_1d(samples_in)
@@ -1059,6 +1060,7 @@ class VAE:
             do_tile = True
 
         if do_tile:
+            comfy.model_management.soft_empty_cache()
             if self.latent_dim == 3:
                 tile = 256
                 overlap = tile // 4