fix(db): Remove backfill migration to fix PostgreSQL enum transaction issue

drizzle-kit migrate runs all pending migrations in a single transaction,
so the new enum value is not committed when the UPDATE tries to use it.

Moved backfill to standalone script: scripts/backfill-referral-legacy.sql
Run this manually after migration 0039 is deployed.

Author: brandonkachen

packages/internal/src/db/migrations/0040_referral_legacy_backfill.sql

@@ -282,12 +282,5 @@
       "tag": "0039_quiet_franklin_storm",
       "breakpoints": true
     },
-    {
-      "idx": 40,
-      "version": "7",
-      "when": 1769650000000,
-      "tag": "0040_referral_legacy_backfill",
-      "breakpoints": true
-    }
   ]
 }

packages/internal/src/db/migrations/meta/_journal.json

@@ -0,0 +1,28 @@
+-- Backfill script for referral_legacy grants
+-- Run this AFTER migration 0039_quiet_franklin_storm.sql has been deployed and committed
+--
+-- This script cannot be part of Drizzle migrations because PostgreSQL requires
+-- new enum values to be committed before they can be used in subsequent statements.
+--
+-- Usage: Connect to your database and run this script manually after deployment
+-- psql $DATABASE_URL -f scripts/backfill-referral-legacy.sql
+
+-- Migrate existing referral grants that have an expiry date to referral_legacy type
+-- (These are the recurring grants from the old referral program)
+UPDATE "credit_ledger" 
+SET "type" = 'referral_legacy', 
+    "priority" = 30
+WHERE "type" = 'referral' 
+  AND "expires_at" IS NOT NULL;
+
+-- Update priority for remaining referral grants (one-time grants) to new priority
+UPDATE "credit_ledger"
+SET "priority" = 50
+WHERE "type" = 'referral'
+  AND "expires_at" IS NULL;
+
+-- Verify the changes
+SELECT "type", COUNT(*), MIN("priority"), MAX("priority")
+FROM "credit_ledger"
+WHERE "type" IN ('referral', 'referral_legacy')
+GROUP BY "type";