feat(onboarding): minimal input: orgnr + moms period is the whole ask (#1952)

* feat(onboarding): minimal input: orgnr + moms period is the whole ask

Two fixes from the third E2E attempt (2026-08-26):

1. accounting_method is now optional in CompanySetupSchema and defaults by
   form in planCompanySetup: aktiebolag = accrual (the norm), enskild
   firma = cash (the common small-EF choice; legal under 3 MSEK, BFL 4
   kap 4 paragraf). The plan flags the default (resolved.accountingMethodDefaulted)
   and gnubok_create_company's preview carries accounting_method_defaulted
   so the readback names it and the user overrides in the same 'ja'.
   Never silent: the preview is the checkpoint. Applies to the MCP tool
   and POST /api/v1/companies (additive; response shows the resolved
   value). The lookup tool's still_to_ask no longer lists it.

2. The agent refused a real orgnr because the user said 'nytt bolag' and
   the registry showed an established company ('Stopp. Numret matchar
   inte ett nytt bolag'): lookup instructions now state that an
   established company with F-skatt/VAT is the NORMAL case (new = new to
   Accounted) and the orgnr is never second-guessed for looking
   established.

Skill + plugin (v1.2.1) updated; API skill regenerated; DECISIONS.md entry.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(onboarding): surface the kontantmetod 3-MSEK condition on the defaulted cash method

Compliance-review finding on #1952: the EF cash default carries a legal
eligibility condition (turnover normally under 3 MSEK, BFL 4 kap 4 §)
that a client not reading the onboarding skill would never see. The
create preview now carries accounting_method_note with the condition
whenever cash was defaulted, and the v1 pitfall states it for API
integrators. The registry cannot verify turnover, so the confirm-time
human check is the gate; the default itself stays (a brand-new EF has
zero turnover by definition).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

app/api/v1/companies/route.ts

@@ -106,6 +106,7 @@ registerEndpoint({
     'first_fiscal_year is only for a company in its first year (BFL 3 kap.: up to 18 months). Omit it for an established company.',
     'Not idempotent, and Idempotency-Key is not honoured on this company-less route: a retry after a network failure creates a second company. List GET /api/v1/companies before retrying.',
     'org_number is required for a VAT-registered company (the invoice momsregistreringsnummer derives from it), and f_skatt must be stated explicitly: F-skatt approval is never assumed.',
+    'accounting_method may be omitted: it then defaults by form (aktiebolag accrual, enskild firma cash) and the response shows the resolved value. The cash default is only legal when turnover normally stays under 3 MSEK (BFL 4 kap 4 §): send accrual explicitly for a larger enskild firma.',
   ],
   example: {
     request: {
@@ -190,7 +191,7 @@ export const POST = withApiV1('companies.create', async (request, ctx) => {
     org_number: (plan.input.settings.org_number as string | null) ?? null,
     vat_registered: setup.vat_registered,
     moms_period: setup.vat_registered ? setup.moms_period ?? null : null,
-    accounting_method: setup.accounting_method,
+    accounting_method: plan.resolved.accountingMethod,
     fiscal_period: {
       start_date: plan.fiscalPeriod.startDate,
       end_date: plan.fiscalPeriod.endDate,