fix: use get_or_create for vertical in import script

backend/import_elgoose.py

@@ -253,17 +253,24 @@ def main():
     print("="*60)
     
     with Session(engine) as session:
-        # 1. Create vertical
+        # 1. Get or create vertical
         print("\n🦆 Creating Goose vertical...")
-        vertical = Vertical(
-            name="Goose",
-            slug="goose",
-            description="Goose is a jam band from Connecticut"
-        )
-        session.add(vertical)
-        session.commit()
-        session.refresh(vertical)
-        print(f"✓ Created vertical (ID: {vertical.id})")
+        vertical = session.exec(
+            select(Vertical).where(Vertical.slug == "goose")
+        ).first()
+        
+        if not vertical:
+            vertical = Vertical(
+                name="Goose",
+                slug="goose",
+                description="Goose is a jam band from Connecticut"
+            )
+            session.add(vertical)
+            session.commit()
+            session.refresh(vertical)
+            print(f"✓ Created vertical (ID: {vertical.id})")
+        else:
+            print(f"✓ Using existing vertical (ID: {vertical.id})")
         
         # 2. Create users
         users = create_users(session)