sched: address R1 findings on shared traversal and resolver threading

src/wf_core/models/input_bindings.py

@@ -205,6 +205,15 @@ def validate_input_expression_limits(
     visit_expression(value, depth=1, location="expression")
 
 
+def _check_expression_limits(value: object) -> object:
+    """Share the budget validator across graph and schedule bindings."""
+    raw_value = (
+        value.model_dump(mode="python") if isinstance(value, BaseModel) else value
+    )
+    validate_input_expression_limits(raw_value)
+    return value
+
+
 class InputExpressionBinding(BaseModel):
     """Assign one recursively composed expression to a node-local target."""
 
@@ -216,11 +225,7 @@ class InputExpressionBinding(BaseModel):
     @field_validator("expression", mode="before")
     @classmethod
     def check_limits(cls, value: object) -> object:
-        raw_value = (
-            value.model_dump(mode="python") if isinstance(value, BaseModel) else value
-        )
-        validate_input_expression_limits(raw_value)
-        return value
+        return _check_expression_limits(value)
 
 
 InputBinding = Annotated[
@@ -262,11 +267,7 @@ class ScheduleInputBinding(BaseModel):
     @field_validator("expression", mode="before")
     @classmethod
     def check_limits(cls, value: object) -> object:
-        raw_value = (
-            value.model_dump(mode="python") if isinstance(value, BaseModel) else value
-        )
-        validate_input_expression_limits(raw_value)
-        return value
+        return _check_expression_limits(value)
 
 
 for _model in (