Salary module improvements (#250)

* 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

* feat: enhance employee management with salary type, tax status, and validation improvements

* feat: Implement AGI submission flow to Skatteverket

- Added AGI submission route to handle the submission process.
- Created AGI client for interacting with Skatteverket's API.
- Introduced AGI mappers to convert salary run data into the required AGI JSON payload format.
- Enhanced API client to support custom base URLs for Skatteverket API requests.
- Added types for AGI submission payload and validation results.
- Implemented tests for AGI mappers to ensure correct payload structure and data handling.

* feat: enhance salary module with Skatteverket integration and update dashboard navigation

* Update app/api/salary/runs/[id]/agi/submit/route.ts

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* Update app/api/salary/runs/[id]/approve/route.ts

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* feat: integrate write permission check and remove Skatteverket extension

---------

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

lib/api/schemas.ts

@@ -636,7 +636,8 @@ export const SalaryLineItemTypeSchema = z.enum([
   'correction', 'other',
 ])
 
-export const CreateEmployeeSchema = z.object({
+// Base employee object (no refinements — safe for .partial())
+const EmployeeSchemaBase = z.object({
   first_name: z.string().min(1).max(200),
   last_name: z.string().min(1).max(200),
   personnummer: z.string().regex(/^\d{12}$/, 'Personnummer måste vara 12 siffror (ÅÅÅÅMMDDNNNN)'),
@@ -667,7 +668,75 @@ export const CreateEmployeeSchema = z.object({
   vaxa_stod_end: isoDate.optional(),
 })
 
-export const UpdateEmployeeSchema = CreateEmployeeSchema.partial()
+export const CreateEmployeeSchema = EmployeeSchemaBase.superRefine((data, ctx) => {
+  // Salary amount required based on salary_type
+  if (data.salary_type === 'monthly' && (data.monthly_salary === undefined || data.monthly_salary === null || data.monthly_salary <= 0)) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Månadslön krävs och måste vara större än 0 för månadslöneform',
+      path: ['monthly_salary'],
+    })
+  }
+  if (data.salary_type === 'hourly' && (data.hourly_rate === undefined || data.hourly_rate === null || data.hourly_rate <= 0)) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Timlön krävs och måste vara större än 0 för timlöneform',
+      path: ['hourly_rate'],
+    })
+  }
+
+  // Tax table required for A-skatt employees (not sidoinkomst)
+  if (data.f_skatt_status === 'a_skatt' && !data.is_sidoinkomst && !data.tax_table_number) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Skattetabell krävs för A-skatt anställda (baseras på folkbokföringskommun)',
+      path: ['tax_table_number'],
+    })
+  }
+
+  // Tax municipality recommended when tax table is set
+  if (data.tax_table_number && !data.tax_municipality) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Folkbokföringskommun bör anges för att dokumentera skattetabellens underlag',
+      path: ['tax_municipality'],
+    })
+  }
+})
+
+export const UpdateEmployeeSchema = EmployeeSchemaBase.partial().superRefine((data, ctx) => {
+  // Only validate salary when salary_type is being changed in this update
+  if (data.salary_type === 'monthly' && data.monthly_salary !== undefined && data.monthly_salary <= 0) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Månadslön måste vara större än 0 för månadslöneform',
+      path: ['monthly_salary'],
+    })
+  }
+  if (data.salary_type === 'hourly' && data.hourly_rate !== undefined && data.hourly_rate <= 0) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Timlön måste vara större än 0 för timlöneform',
+      path: ['hourly_rate'],
+    })
+  }
+
+  // If setting salary_type, require the corresponding salary field
+  if (data.salary_type === 'monthly' && !('monthly_salary' in data)) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Månadslön måste anges vid byte till månadslöneform',
+      path: ['monthly_salary'],
+    })
+  }
+  if (data.salary_type === 'hourly' && !('hourly_rate' in data)) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Timlön måste anges vid byte till timlöneform',
+      path: ['hourly_rate'],
+    })
+  }
+})
 
 export const CreateSalaryRunSchema = z.object({
   period_year: z.number().int().min(2020).max(2100),