Fix employee time conflicts

backend/src/main/resources/db/migration/V17__normalize_appointment_pets.sql

@@ -0,0 +1,28 @@
+-- V17: Normalize legacy appointmentPet data into customer_pet and appointment_customer_pet
+
+-- Step 1: Ensure a customer_pet exists for every pet linked in appointmentPet
+-- Note: pet species and breed might be null in pet table, but we copy them over if present
+INSERT INTO customer_pet (customer_id, pet_name, species, breed)
+SELECT DISTINCT a.customerId, p.petName, p.petSpecies, p.petBreed
+FROM appointmentPet ap
+JOIN appointment a ON a.appointmentId = ap.appointmentId
+JOIN pet p ON p.petId = ap.petId
+WHERE NOT EXISTS (
+    SELECT 1 FROM customer_pet cp 
+    WHERE cp.customer_id = a.customerId AND cp.pet_name = p.petName
+);
+
+-- Step 2: Link the appointment to the customer_pet
+INSERT INTO appointment_customer_pet (appointment_id, customer_pet_id)
+SELECT ap.appointmentId, cp.customer_pet_id
+FROM appointmentPet ap
+JOIN appointment a ON a.appointmentId = ap.appointmentId
+JOIN pet p ON p.petId = ap.petId
+JOIN customer_pet cp ON cp.customer_id = a.customerId AND cp.pet_name = p.petName
+WHERE NOT EXISTS (
+    SELECT 1 FROM appointment_customer_pet acp 
+    WHERE acp.appointment_id = ap.appointmentId AND acp.customer_pet_id = cp.customer_pet_id
+);
+
+-- Step 3: Remove the old legacy relationships so it strictly uses the new ones
+DELETE FROM appointmentPet;