MPDynamic: force load flux img_in weight (Fixes flux1 canny+depth lora crash) (#12446)

* lora: add weight shape calculations.

This lets the loader know if a lora will change the shape of a weight
so it can take appropriate action.

* MPDynamic: force load flux img_in weight

This weight is a bit special, in that the lora changes its geometry.
This is rather unique, not handled by existing estimate and doesn't
work for either offloading or dynamic_vram.

Fix for dynamic_vram as a special case. Ideally we can fully precalculate
these lora geometry changes at load time, but just get these models
working first.

comfy/weight_adapter/base.py

@@ -49,6 +49,12 @@ class WeightAdapterBase:
         """
         raise NotImplementedError
 
+    def calculate_shape(
+        self,
+        key
+    ):
+        return None
+
     def calculate_weight(
         self,
         weight,