Move inline comfy.context_windows imports to top-level in model_base.py (#13083)

The recent PR that added resize_cond_for_context_window methods to
model classes used inline 'import comfy.context_windows' in each
method body. This moves that import to the top-level import section,
replacing 4 duplicate inline imports with a single top-level one.

Author: Kosinkadink

comfy/model_base.py

@@ -21,6 +21,7 @@
 import torch
 import logging
 import comfy.ldm.lightricks.av_model
+import comfy.context_windows
 from comfy.ldm.modules.diffusionmodules.openaimodel import UNetModel, Timestep
 from comfy.ldm.cascade.stage_c import StageC
 from comfy.ldm.cascade.stage_b import StageB
@@ -1383,7 +1384,6 @@ def extra_conds(self, **kwargs):
 
     def resize_cond_for_context_window(self, cond_key, cond_value, window, x_in, device, retain_index_list=[]):
         if cond_key == "vace_context":
-            import comfy.context_windows
             return comfy.context_windows.slice_cond(cond_value, window, x_in, device, temporal_dim=3, retain_index_list=retain_index_list)
         return super().resize_cond_for_context_window(cond_key, cond_value, window, x_in, device, retain_index_list=retain_index_list)
 
@@ -1441,7 +1441,6 @@ def extra_conds(self, **kwargs):
 
     def resize_cond_for_context_window(self, cond_key, cond_value, window, x_in, device, retain_index_list=[]):
         if cond_key == "audio_embed":
-            import comfy.context_windows
             return comfy.context_windows.slice_cond(cond_value, window, x_in, device, temporal_dim=1)
         return super().resize_cond_for_context_window(cond_key, cond_value, window, x_in, device, retain_index_list=retain_index_list)
 
@@ -1463,7 +1462,6 @@ def extra_conds(self, **kwargs):
         return out
 
     def resize_cond_for_context_window(self, cond_key, cond_value, window, x_in, device, retain_index_list=[]):
-        import comfy.context_windows
         if cond_key == "face_pixel_values":
             return comfy.context_windows.slice_cond(cond_value, window, x_in, device, temporal_dim=2, temporal_scale=4, temporal_offset=1)
         if cond_key == "pose_latents":
@@ -1508,7 +1506,6 @@ def extra_conds_shapes(self, **kwargs):
 
     def resize_cond_for_context_window(self, cond_key, cond_value, window, x_in, device, retain_index_list=[]):
         if cond_key == "audio_embed":
-            import comfy.context_windows
             return comfy.context_windows.slice_cond(cond_value, window, x_in, device, temporal_dim=1)
         return super().resize_cond_for_context_window(cond_key, cond_value, window, x_in, device, retain_index_list=retain_index_list)