fix(salary): book lonevaxling pension provision from frozen run snapshot (#1382)

The book flow never populated pension_contribution/pension_slp, so a
gross_deduction_pension line item reduced the salary entry but the
7410/2740 pension provision and 7533/2514 SLP lines were never posted.
Derive both at the createSalaryRunEntries boundary from the run's frozen
calculation_params.slpRate snapshot so the dashboard, MCP and v1 booking
paths all emit the pension verifikat, and reuse the exact 1.058 factor
via calculateLoneVaxlingPensionProvision shared with the planning
calculator.

Fixes #317

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

lib/salary/book-run.ts

@@ -151,6 +151,9 @@ async function bookLoadedRun(
       total_net: run.total_net as number,
       total_avgifter: run.total_avgifter as number,
       total_vacation_accrual: run.total_vacation_accrual as number,
+      // Use the exact payroll-rate snapshot approved with this run. Reading
+      // current config here could change SLP between calculation and booking.
+      calculation_params: run.calculation_params as Record<string, unknown> | null,
       employees: roster.map((sre) => ({
         employee_id: sre.employee_id,
         employment_type: sre.employee?.employment_type || 'employee',