Fix: use identity check for metric model resolution in all three fallback loops

Author: nicosuave

sidemantic/sql/generator.py

@@ -2200,7 +2200,7 @@ def resolve_ratio_ref(ref: str) -> str:
                 metric_model_name = model_context
                 if not metric_model_name:
                     for m_name, m in self.graph.models.items():
-                        if metric in m.metrics:
+                        if any(metric is mm for mm in m.metrics):
                             metric_model_name = m_name
                             break
 
@@ -2338,7 +2338,7 @@ def _generate_retention_query(
         # Find the model that owns this metric if not already found
         if not model:
             for m_name, m in self.graph.models.items():
-                if metric in m.metrics:
+                if any(metric is mm for mm in m.metrics):
                     model = m
                     break
             if not model:
@@ -2545,7 +2545,7 @@ def _generate_conversion_query(
         if not model:
             # First, try to find which model has this conversion metric defined
             for m_name, m in self.graph.models.items():
-                if metric in m.metrics:
+                if any(metric is mm for mm in m.metrics):
                     model = m
                     break