fix: SIE import voucher range bugs + remove describe transaction (#161)

* fix: fix SIE import voucher range bugs from multi-tenant migration and remove describe transaction feature

- Fix reserve_voucher_range RPC parameter mismatch (p_user_id → p_company_id) causing duplicate voucher errors
- Fix create-accounts onConflict from user_id to company_id
- Add reserve-then-adjust pattern: pre-reserve voucher range before batch insert, release unused range on partial failure
- Add release_voucher_range DB function for safe rollback
- Remove DescribeTransactionDialog, describe/batch-describe API routes, and related schemas (feature superseded)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address Greptile review — voucher range race condition and orphaned entries

- Add p_reserved_highest upper-bound guard to release_voucher_range to prevent
  rolling back past numbers claimed by concurrent operations
- Move highestInsertedVoucher tracking to after both headers AND lines succeed,
  preventing orphaned journal entries with no lines from being counted as "used"

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/api/import/sie/create-accounts/route.ts

@@ -108,7 +108,7 @@ export async function POST(request: Request) {
       const { data: upserted, error } = await supabase
         .from('chart_of_accounts')
         .upsert(batch, {
-          onConflict: 'user_id,account_number',
+          onConflict: 'company_id,account_number',
           ignoreDuplicates: true,
           count: 'exact',
         })