fix(bookkeeping): a following year's own IB no longer blocks nollställ, and a re-dated räkenskapsår gets the right name (#2286)

Customer report (Aisen & Adison AB, 2026-09-03): Fortnox years 2024-2026
imported first, then the first year 2022/2023 backfilled. Two bugs surfaced.

1. The backfilled year was saved as "Räkenskapsår 2027": CreatePeriodDialog
   seeds the next forward year and kept that name when the user re-dated the
   form. The name now follows the typed dates until the user edits the name
   (fiscalYearName exported from suggest-fiscal-period).

2. Nollställ of the backfilled year was refused with next_year_dependency
   because 2024 carried an opening-balance verifikat. Any IB in the next year
   counted as reliance, so a backfilled year could never be reset, while a
   next year WITHOUT an IB (whose balansrapport really rolls from this year)
   was allowed. Migration 20260904163000 redefines fiscal_year_reset_snapshot:
   the block fires only when the next year is locked, closed or has its own
   closing entry; a bokslut-generated IB is still refused via this year's
   closing_entry_id (year_end_state). The snapshot returns next_period
   {id, name, has_opening_balances} and the dialog states that the following
   year's IB stays as it is.

pg-real: reset-fiscal-year.pg.test.ts pins the narrowed guard (closed next
year, next year with closing entry, next year with its own IB survives the
reset untouched).

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

lib/core/bookkeeping/__tests__/fiscal-year-reset.test.ts

@@ -35,6 +35,7 @@ const SNAPSHOT = {
     period_end: '2026-12-31',
   },
   counts: { vouchers: 7, documents_to_detach: 2 },
+  next_period: { id: 'period-2', name: '2027', has_opening_balances: true },
 }
 
 describe('getFiscalYearResetEligibility', () => {
@@ -52,6 +53,7 @@ describe('getFiscalYearResetEligibility', () => {
         blockers: [],
         period: SNAPSHOT.period,
         counts: SNAPSHOT.counts,
+        next_period: SNAPSHOT.next_period,
       },
     })
     expect(supabase.rpc).toHaveBeenCalledWith('get_fiscal_year_reset_eligibility', {

lib/core/bookkeeping/fiscal-year-reset.ts

@@ -56,6 +56,7 @@ export async function getFiscalYearResetEligibility(
       blockers: result.blockers ?? [],
       period: result.period!,
       counts: result.counts ?? { vouchers: 0, documents_to_detach: 0 },
+      next_period: result.next_period ?? null,
     },
   }
 }