fix: migration 040 — drop old loyalty_tier check constraint before renaming standard→bronze

The guests table had CHECK (loyalty_tier IN ('standard','silver','gold','platinum'))
but the UI expects 'bronze' not 'standard'. Drop the old constraint, migrate
'standard' rows to 'bronze', then add the correct constraint.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/migrations/040_fixes.sql

@@ -14,7 +14,16 @@ CREATE UNIQUE INDEX IF NOT EXISTS uq_chat_rooms_general_per_hotel
   ON chat_rooms (hotel_id)
   WHERE type = 'general';
 
--- Fix 2: normalize loyalty_tier values that don't match our 4 tiers
+-- Fix 2: replace 'standard' tier with 'bronze' (the UI uses bronze/silver/gold/platinum)
+-- Drop the old check constraint that only allows 'standard' instead of 'bronze'
+ALTER TABLE guests DROP CONSTRAINT IF EXISTS guests_loyalty_tier_check;
+
+-- Add the correct constraint
+ALTER TABLE guests
+  ADD CONSTRAINT guests_loyalty_tier_check
+  CHECK (loyalty_tier IN ('bronze', 'silver', 'gold', 'platinum'));
+
+-- Migrate existing 'standard' rows to 'bronze'
 UPDATE guests
 SET loyalty_tier = 'bronze'
 WHERE loyalty_tier NOT IN ('bronze', 'silver', 'gold', 'platinum');