Fix SIE multi-year P&L accumulation, Fortnox supplier filter, processing_history (#267)

* fix: prevent P&L accumulation when importing multi-year SIE files

The opening-balance fallback summed all prior journal lines without
distinguishing balance sheet (class 1-2) from P&L (class 3-8). When
users imported one SIE file per year without running year-end closing
between them, resultatkonton accumulated across years instead of
resetting at each räkenskapsårsskifte. Reported by a customer.

Skip class 3-8 in the fallback path. P&L accounts must reset to zero
each fiscal year (årets resultat → 2099 → equity).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix: only import unpaid supplier invoices from Fortnox

Fortnox's /supplierinvoices list endpoint doesn't reliably expose
FullyPaid, which caused historic paid invoices to be imported as
unpaid. Switch to the ?filter=unpaid query and surface that scope
in the migration options UI.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* feat: add processing_history table for behandlingshistorik

Append-only event log per BFNAR 2013:2 kap 8. Includes:
- processing_history table with seq, correlation/causation chaining,
  aggregate (Document/BankTransaction/MatchProposal/Verifikation/etc.),
  open event_type validated against processing_event_types registry.
- Immutability via audit_log_immutable trigger (no UPDATE/DELETE).
- RLS scoped to user_company_ids; writes via service role only.
- appendProcessingHistory() helper with PII guard rejecting payloads
  containing personnummer/orgnr patterns.
- Shared TS types in types/index.ts.

No consumers wired yet — this is the persistence layer only.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* chore: add swedish-project-accounting skill

Reference skill covering projektredovisning: dimensional tagging,
WIP accounting, K2/K3 revenue recognition (successiv vinstavräkning,
färdigställandemetoden), entreprenadavtal, BAS patterns (1470,
1620, 2420, 2450, 4970), and SIE4 #DIM 6 encoding.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix: rename processing_history migration to avoid timestamp collision

Main already has 20260418120000_allow_retroactive_first_fiscal_year.sql
from #265. Bumping this migration's timestamp to 20260418130000 to
keep schema_migrations.version unique.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix: address Greptile review on processing_history

- Add BEFORE DELETE immutability trigger so the service role can't
  silently remove rows. Mirrors the pattern from migration 014
  (audit_log_no_update + audit_log_no_delete) and satisfies the
  immutability claim in BFNAR 2013:2 kap 8. Delivered as a follow-up
  migration since the original was already applied in some envs.

- Tighten PII patterns with \b word boundaries to avoid false
  positives on Bankgiro numbers (123456-7890) and invoice references
  like 202312-1234.

- Extend PII validation to actor.label, which previously bypassed
  the payload guard despite the docblock explicitly forbidding
  names/emails/personnummer there.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/extensions/general/ArcimMigrationWorkspace.tsx

@@ -753,6 +753,7 @@ function OptionsStep({
   options,
   sieAvailable,
   sieData,
+  provider,
   onChange,
   onStart,
   onBack,
@@ -760,6 +761,7 @@ function OptionsStep({
   options: MigrationOptions
   sieAvailable: boolean
   sieData: SIEData | null
+  provider: ArcimProvider | null
   onChange: (options: MigrationOptions) => void
   onStart: () => void
   onBack: () => void
@@ -881,7 +883,9 @@ function OptionsStep({
           <OptionRow
             icon={<FileText className="h-4 w-4" />}
             label="Leverantörsfakturor"
-            description="Alla leverantörsfakturor (betalda och obetalda)"
+            description={provider === 'fortnox'
+              ? 'Endast obetalda leverantörsfakturor hämtas. Historiska betalda fakturor finns kvar i Fortnox.'
+              : 'Alla leverantörsfakturor (betalda och obetalda)'}
             checked={options.importSupplierInvoices}
             onChange={() => toggleOption('importSupplierInvoices')}
           />
@@ -2006,6 +2010,7 @@ export default function ArcimMigrationWorkspace(_props: WorkspaceComponentProps)
           options={migrationOptions}
           sieAvailable={preview?.sieAvailable ?? false}
           sieData={sieData}
+          provider={preview?.consent.provider ?? null}
           onChange={setMigrationOptions}
           onStart={handleStartMigration}
           onBack={() => preview?.sieAvailable ? setStep('mapping') : setStep('preview')}