feat(salary): repay utlägg with the salary as a tax-free payslip line (#2361)

* feat(salary): repay utlägg with the salary as a tax-free payslip line (#2331)

- expense_reimbursement line type: kostnadsersättning outside gross, tax,
  avgifter and the AGI. The engine adds tax-free reimbursements (utlägg,
  skattefritt traktamente, skattefri milersättning) to the net payout only.
- booking debits the claim's liability account (2820) on top of gross,
  never a 7xxx cost; a run that only repays utlägg posts 2820 D / 1930 K
  instead of being treated as a nollkörning
- salary_line_items.source_expense_claim_id (tenant-scoped FK, cascade,
  one payslip line per claim); settle_expense_claims_via_salary_run marks
  the claims paid with an expense_payout_batches row pointing at the
  salary verifikat, no second verifikat, idempotent on retry; wired into
  bookLoadedRun and the v1 book route with a pre-check before posting
- create_expense_payout_batch refuses claims scheduled on a payslip
  (ON_PAYSLIP); deleteExpenseClaim refuses once the run has left draft
- "Lägg till utlägg" on the employee row of a draft run; the payslip page
  labels and removes the lines
- pg-real: tests/pg/utlagg-via-lon.pg.test.ts + ON_PAYSLIP case

Claude-Session: https://claude.ai/code/session_01LvMaHcTnwAfxzgYD1fGYX1
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

* fix(salary): PR #2361 review: claim delete cannot cascade into a booked payslip; AGI excludes the utlägg line

- salary_line_items_source_expense_claim_fkey is ON DELETE RESTRICT (edited
  in the unmerged 20260906210300): the database refuses to delete a claim a
  payslip line still references, whichever path issues the DELETE
- deleteExpenseClaim removes the draft line first (before the storno) and
  keeps refusing with ON_PAYSLIP once the run has left draft
- pg-real: delete refused with 23503 on a booked and on a draft run; the
  app order (line, then claim) succeeds
- unit: AGI builder keeps FK011/FK001/FK487 and emits no benefit field for
  an expense_reimbursement line (FK011 derives from sre.gross_salary; only
  benefit_* types are read from line items)

Claude-Session: https://claude.ai/code/session_01LvMaHcTnwAfxzgYD1fGYX1
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

---------

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

app/api/v1/companies/[companyId]/salary-runs/[id]/book/route.ts

@@ -34,6 +34,11 @@ import { withApiV1 } from '@/lib/api/v1/with-api-v1'
 import { v1ErrorResponse, v1ErrorResponseFromCode } from '@/lib/api/v1/errors'
 import { checkPeriodLock } from '@/lib/api/v1/check-period-lock'
 import { createSalaryRunEntries } from '@/lib/salary/salary-entries'
+import {
+  assertLinkedExpenseClaimsOpen,
+  rosterHasLinkedExpenseClaims,
+  settleExpenseClaimsForBookedRun,
+} from '@/lib/salary/expense-claim-lines'
 import { isFSkattStatus } from '@/lib/salary/declared-avgifter'
 import { syncVacationLedgerForEmployees } from '@/lib/salary/vacation-ledger'
 import { isBookkeepingError } from '@/lib/bookkeeping/errors'
@@ -169,6 +174,20 @@ export const POST = withApiV1<{ params: Promise<{ companyId: string; id: string
       })
     }
 
+    // Utlägg repaid with this salary (#2331): every linked claim must still
+    // be open BEFORE anything is posted (mirrors lib/salary/book-run.ts).
+    const claimsCheck = await assertLinkedExpenseClaimsOpen(
+      ctx.supabase,
+      ctx.companyId!,
+      employees as Array<{ employee_id: string; line_items: Array<Record<string, unknown>> | null }>,
+    )
+    if (!claimsCheck.ok) {
+      return v1ErrorResponseFromCode(claimsCheck.code, ctx.log, {
+        requestId: ctx.requestId,
+        details: claimsCheck.details,
+      })
+    }
+
     if (ctx.dryRun) {
       // Without invoking the engine we can't get real voucher numbers, but
       // we CAN preview the would-be state transition + the expected entry
@@ -371,6 +390,28 @@ export const POST = withApiV1<{ params: Promise<{ companyId: string; id: string
       })
     }
 
+    // Utlägg repaid with this salary: mark the claims paid with a payout
+    // batch pointing at the salary verifikat (mirrors lib/salary/book-run.ts;
+    // the verifikat is posted, so a failure is logged, never rolled back).
+    if (
+      rosterHasLinkedExpenseClaims(
+        employees as Array<{ employee_id: string; line_items: Array<Record<string, unknown>> | null }>,
+      )
+    ) {
+      const settled = await settleExpenseClaimsForBookedRun(ctx.supabase, {
+        companyId: ctx.companyId!,
+        userId: ctx.userId,
+        salaryRunId,
+      })
+      if (!settled.ok) {
+        ctx.log.error(
+          'expense claims NOT settled after salary booking: run is booked with a 2820 debit but the claims are still open; re-run settle_expense_claims_via_salary_run',
+          new Error(settled.detail ?? settled.code),
+          { salaryRunId, companyId: ctx.companyId, code: settled.code },
+        )
+      }
+    }
+
     // Final refresh of the payslip's "Ackumulerat" snapshot, mirroring
     // lib/salary/book-run.ts. Non-fatal: YTD is display only and never
     // reaches a verifikation.