fix medipost_actions constraint

supabase/migrations/20250923143000_fix_medipost_actions_unique_constraint.sql

@@ -0,0 +1,12 @@
+-- Fix medipost_actions unique constraint to work with ON CONFLICT
+-- The previous partial index cannot be used with ON CONFLICT clause
+
+-- Drop the existing partial unique index
+DROP INDEX IF EXISTS "medreport"."medipost_actions_unique_by_private_message_id";
+
+-- Create a proper unique constraint that can be used with ON CONFLICT
+-- PostgreSQL unique constraints allow multiple NULL values by default
+-- This will enforce uniqueness for non-NULL values while allowing multiple NULLs
+ALTER TABLE "medreport"."medipost_actions" 
+ADD CONSTRAINT "medipost_actions_unique_by_private_message_id" 
+UNIQUE ("medipost_private_message_id");