Revert budget to net DEBIT-CREDIT formula, remove fix-cc-types endpoint

Budget formula correctly adds DEBIT (CC charges stored from positive CSV
values) and subtracts CREDIT (refunds from negative CSV values).
Remove the fix-cc-types endpoint which was flipping CC transaction types
and causing charges to appear as CREDIT.

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

src/app/(app)/dashboard/page.tsx

@@ -42,7 +42,7 @@ export default async function DashboardPage({ searchParams }: { searchParams: Se
     }),
     prisma.$queryRaw<{ budgetId: string; total: bigint }[]>`
       SELECT t."budgetId",
-        COALESCE(SUM(CASE WHEN t.type = 'DEBIT' THEN t."amountCents" ELSE 0 END), 0)::bigint AS total
+        COALESCE(SUM(CASE WHEN t.type = 'DEBIT' THEN t."amountCents" ELSE -t."amountCents" END), 0)::bigint AS total
       FROM "Transaction" t
       JOIN "Account" a ON t."accountId" = a.id
       WHERE a."userId" = ${userId}