feat(mileage): körjournal with milersättning booking, MCP tools and CSV export (#1448)

* feat(mileage): körjournal with milersättning booking, MCP tools and CSV export

New mileage_trips table (RLS, booked-delete trigger per BFL retention),
lib/mileage service reusing the payroll schablon rates, /api/mileage routes
(trips CRUD, period booking to 7331, salary-run push, körjournal CSV),
Körjournal dashboard page + nav, and three staged MCP tools (search-only
catalog). Trips book as one verifikat per period via the engine; salary
path inserts mileage_taxfree line items. mileage_trips classified in the
full-archive export.

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

* refactor(mileage): use shared roundOre helper per tightened ratchet baseline

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

* fix(mileage): pending_operations op-type migration + Swedish review findings

- New migration pair adds log_mileage_trip/book_mileage_period to the
  pending_operations operation_type CHECK (pg-real audit).
- bookMileagePeriod refuses a period spanning several employees and names
  the employee in the verifikationstext when scoped (BFL motpart).
- vehicle_registration required for förmånsbil trips (schema, service,
  MCP staging, UI surfaces the field).

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

* fix(mileage): claim-first booking, CSV injection guard and driver column

- bookMileagePeriod claims trips (draft to booked CAS) before creating the
  verifikat, so a concurrent second booking loses the race instead of
  double-booking; claim reverts if verifikat creation fails.
- Körjournal CSV neutralizes formula-injection triggers (OWASP) and adds a
  Förare column naming the employee per trip.

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

* fix(mileage): resolve CodeRabbit + Swedish review round: race, drift and hardening

- Copying a round trip no longer re-doubles the stored distance.
- pushMileageToSalaryRun claims trips before inserting line items (retry can
  no longer double-pay); CLAIM_LOST replaces misleading NO_TRIPS on lost races.
- Booked trips are DB-immutable via a BEFORE UPDATE trigger (new migration
  20260807113215): only claim/link/revert transitions and notes edits pass.
- Cross-year periods rejected (schablon rates are per calendar year); payroll
  config year read from the date string, not TZ-dependent getFullYear().
- MCP staged bookings freeze the previewed trip set (trip_ids in params) and
  the commit fails on drift; validation errors return 400, not 500.
- PATCH enforces the förmånsbil regnr rule on the effective row; export
  validates dates before they reach the Content-Disposition header; employee_id
  is verified company-scoped on trip creation; stale orphaned claims released.
- UI: fetch flags reset in finally; ICU plural for draft summary; distance
  stored at the column's 1-decimal precision.
- Tests: [id] route suite, pushMileageToSalaryRun suite, claim-race, drift,
  cross-year and update-trigger pg cases.

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

* fix(mileage): revert-to-draft must clear salary_run_id at the trigger level

New migration 20260807114924 replaces the booked-immutability function: a
booked -> draft revert now rejects rows keeping salary_run_id, closing the
DB-level double-pay path CodeRabbit flagged. pg test pins both directions;
the CLAIM_LOST unit test now asserts the revert.

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

* fix(mileage): company-scope employee_id on PATCH (Superagent P2)

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

* test(mileage): valid v4 uuid in cross-company employee PATCH test

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

---------

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

components/dashboard/DashboardNav.tsx

@@ -45,6 +45,7 @@ import {
   PanelLeftClose,
   Library,
   BookCheck,
+  Car,
 } from 'lucide-react'
 import { getBranding } from '@/lib/branding/service'
 import { ENABLED_EXTENSION_IDS as _ENABLED_EXTENSION_IDS } from '@/lib/extensions/_generated/enabled-extensions'
@@ -114,6 +115,7 @@ type NavLabelKey =
   | 'reports'
   | 'import'
   | 'salary'
+  | 'mileage'
   | 'employees'
   | 'vat_declaration'
   | 'skattekonto'
@@ -192,6 +194,7 @@ const navItems: NavItem[] = [
   { href: '/invoices', labelKey: 'invoices', icon: ReceiptText, group: 'arbeta' },
   { href: '/supplier-invoices', labelKey: 'supplier_invoices', icon: Wallet, group: 'arbeta' },
   { href: '/salary', labelKey: 'salary', icon: HandCoins, group: 'arbeta', employerOnly: true },
+  { href: '/mileage', labelKey: 'mileage', icon: Car, group: 'arbeta' },
   // Analys: read the numbers.
   { href: '/kpi', labelKey: 'kpi', icon: TrendingUp, group: 'analys' },
   { href: '/reports', labelKey: 'reports', icon: BarChart3, group: 'analys' },