feat(salary): öresavrundning of net pay to whole kronor (#1609)

* feat(salary): öresavrundning of net pay to whole kronor

Some banks reject salary payment files whose amounts carry öre. New
company_settings.salary_net_rounding toggle (off by default): the engine
rounds each net payout up to the next whole krona, never down, and emits
a derived oresavrundning line item (semesterersattning pattern) that
debits 3740 Öres- och kronutjämning so the salary entry stays balanced.
Gross, tax and avgifter are untouched, so AGI/KU are unaffected. Payment
files (pain.001 + Bankgirot LB) get whole-krona amounts via the rounded
net_salary. Toggle in salary settings; payslip and run detail show the
line item.

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

* fix(salary): keep employer cost on the shared definition; block manual rounding lines

Skeptic findings on the öresavrundning commit: (1) the engine included
netRounding in totalEmployerCost while payslip summary, KPI cards and
lönejournal recompute the figure from stored columns, printing two
different totals on the same payslip; employer cost now stays on the
shared definition and the öre cost is carried by the 3740 ledger line.
(2) 'oresavrundning' is excluded from the line-item create/update
schemas: it is the only item type the booking keeps out of the gross
reconciliation, so a manually created row would structurally unbalance
the salary verifikat.

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

* fix(salary): add the item_type CHECK as NOT VALID, validate separately

Compliance-swarm finding (SOC 2 CC8.1): the CHECK re-add scanned
salary_line_items under the ADD's ACCESS EXCLUSIVE lock. Split per the
house pattern (DECISIONS.md 2026-07-13): 20260813143000 re-adds the
constraint NOT VALID, new 20260813143001 validates it under SHARE UPDATE
EXCLUSIVE in its own transaction. The list is a strict superset of the
previous CHECK, so validation cannot fail. Both files are branch-only,
so editing in place is within the never-modify-shipped rule.

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

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

types/index.ts

@@ -452,6 +452,9 @@ export interface CompanySettings {
   preferred_payment_format: 'bg_lb' | 'pain001'
   salary_pay_day: number
   salary_default_bank: 'swedbank' | 'seb' | 'handelsbanken' | 'nordea' | 'other' | null
+  // Öresavrundning (migration 20260813143000): round each net payout up to
+  // whole kronor; the 0-99 öre diff books on 3740 via a derived line item.
+  salary_net_rounding: boolean
 
   // Sandbox
   is_sandbox: boolean
@@ -4235,6 +4238,7 @@ export type SalaryLineItemType =
   | 'mileage_taxfree' | 'mileage_taxable'
   | 'net_deduction_advance' | 'net_deduction_union' | 'net_deduction_benefit_payment'
   | 'net_deduction_other'
+  | 'oresavrundning'
   | 'correction' | 'other'
 
 export type ShiftPremiumItemType =