fix(graph): upsert in create_function_graph — reuse existing graph by (store_id, name)

Same pattern as the store lookup above: SELECT existing graph by
(store_id, name) before INSERT. Re-importing a graph with the same
name returns the existing graph_id instead of hitting
idx_platform_function_graphs_unique_name.

Author: pyramation

pgpm/constructive-compute/deploy/schemas/constructive_compute_public/procedures/platform_create_function_graph/procedure.sql

@@ -31,19 +31,25 @@ BEGIN
     RETURNING id INTO v_store_id;
     PERFORM "constructive_platform_function_graph_public".init_empty_repo(platform_create_function_graph.database_id, v_store_id);
   END IF;
-  INSERT INTO "constructive_compute_public".platform_function_graphs (
-    database_id,
-    store_id,
-    name,
-    description,
-    context,
-    entity_id,
-    created_by,
-    definitions_commit_id
-  )
-  VALUES
-    (platform_create_function_graph.database_id, v_store_id, platform_create_function_graph.name, platform_create_function_graph.description, platform_create_function_graph.context, platform_create_function_graph.entity_id, platform_create_function_graph.created_by, platform_create_function_graph.definitions_commit_id)
-  RETURNING id INTO v_graph_id;
+  SELECT g.id
+  FROM "constructive_compute_public".platform_function_graphs AS g
+  WHERE
+    g.store_id = v_store_id AND g.name = platform_create_function_graph.name INTO v_graph_id;
+  IF v_graph_id IS NULL THEN
+    INSERT INTO "constructive_compute_public".platform_function_graphs (
+      database_id,
+      store_id,
+      name,
+      description,
+      context,
+      entity_id,
+      created_by,
+      definitions_commit_id
+    )
+    VALUES
+      (platform_create_function_graph.database_id, v_store_id, platform_create_function_graph.name, platform_create_function_graph.description, platform_create_function_graph.context, platform_create_function_graph.entity_id, platform_create_function_graph.created_by, platform_create_function_graph.definitions_commit_id)
+    RETURNING id INTO v_graph_id;
+  END IF;
   RETURN v_graph_id;
 END;
 $_PGFN_$ LANGUAGE plpgsql VOLATILE SECURITY INVOKER;