Salary module (#245)

* feat: implement salary module with personnummer encryption, salary entries, tax tables, and AGI tracking

- Added personnummer encryption and decryption functions for secure storage.
- Created salary entries handling for journal entries including gross salary, tax withholding, and employer contributions.
- Implemented tax table lookup functionality for calculating tax amounts based on monthly income.
- Developed SQL migration for salary module including tables for payroll configuration, tax rates, employees, salary runs, salary run employees, salary line items, and AGI declarations.
- Established row-level security policies for all new tables to ensure company-scoped access.

* feat: add salary calculation modules for 2026

- Implemented engångsskatt calculation for one-time payments with tax brackets.
- Added löneväxling functionality for salary sacrifice to pension, including employer savings and warnings.
- Created pain.001 generator for salary batch payments in compliance with Swedish banking standards.
- Developed PDF template for payslips, including detailed breakdowns and employer costs.
- Generated seed data for Swedish tax tables for 2026, including SQL insert statements.
- Implemented traktamente calculations for per diem and mileage allowances, adhering to Skatteverket regulations.
- Added seed script for populating tax tables in the database.

* feat: Update meal reduction percentages in traktamente calculation

fix: Remove obsolete seed script for 2026 tax tables

feat: Extend SalaryRunStatus type to include 'corrected' status

feat: Implement KU10 XML generation endpoint for annual employee income statements

feat: Add endpoint for creating corrections to booked salary runs

feat: Implement endpoint for sending payslip PDFs to employees

feat: Create KU10 XML generator for annual reporting

feat: Add salary transaction matcher for auto-linking bank transactions to salary entries

chore: Add database migration for salary correction support

* feat: replace select elements with custom Select component for employment and salary types

* feat: enhance salary calculations with pension entry and avgifter category support

components/settings/SettingsSidebar.tsx

@@ -29,6 +29,7 @@ export function SettingsNav({ isSandbox }: { isSandbox?: boolean }) {
     { href: '/settings/tax', label: 'Skatt', show: hasCompany },
     { href: '/settings/team', label: 'Lag', show: false },
     { href: '/settings/banking', label: 'Bank (PSD2)', show: hasCompany && !isSandbox && hasBankingExtension },
+    { href: '/settings/salary', label: 'Löner', show: hasCompany && company?.entity_type === 'aktiebolag' },
     { href: '/settings/templates', label: 'Mallar', show: hasCompany },
     { href: '/settings/account', label: 'Konto', show: true },
     { href: '/settings/api', label: 'API', show: hasCompany && hasMcpExtension },