Clean up upscale model options

app.py

@@ -577,9 +577,8 @@ def model_choices(models):
 
 def upscale_model_choices(models):
     return [
-        ("Default", DEFAULT_UPSCALE_MODEL),
         ("None", ""),
-        *[(name, name) for name in models if name != DEFAULT_UPSCALE_MODEL],
+        *[(name, name) for name in models],
     ]
 
 
@@ -1834,7 +1833,12 @@ def generate_matrix_cell(body):
 
 
 def model_options(kind, local):
-    return sorted(set(local) | remote_models[kind].keys(), key=str.casefold)
+    local = [local] if isinstance(local, str) else local
+    names = set(local) | remote_models[kind].keys()
+    return sorted(
+        (name for name in names if Path(name).suffix.casefold() in MODEL_SUFFIXES),
+        key=str.casefold,
+    )
 
 
 def generate_images(request, from_api=True):