feat(T04): contact management + USt-IdNr. validation + contact UI

- Contact model: company, role (kaeufer/verkaeufer/beide), soft-delete
- ContactPerson model: 1:N relation with CASCADE delete
- USt-IdNr. validation: DE + 10 EU countries
- Contact CRUD: 7 API endpoints with RBAC, search/filter/paginate
- Frontend: ContactList, ContactForm, ContactDetail with EU/Inland toggle
- 73 backend tests (91% coverage), 20 frontend tests

.a0/current_status.md

@@ -1,31 +1,30 @@
 # Current Status
 
-**Task**: T02 – Vehicle Management + mobile.de Push + Vehicle UI
+**Task**: T04 – Kontakt-/Kundenverwaltung + Contact UI
 **Status**: COMPLETED
 **Date**: 2026-07-14
 
 ## Summary
-Vehicle CRUD API with pagination/filtering/sorting, mobile.de push integration, and full frontend UI implemented.
+Contact management backend (CRUD, search, filter, pagination, soft-delete, contact persons, USt-IdNr. validation) and frontend (ContactList, ContactForm, ContactDetail with EU/Inland toggle) implemented.
 
 ## Backend (COMPLETED)
-- Vehicle model: UUID PK, all fields per spec (make, model, fin CHECK len=17, year, first_registration, power_kw, power_hp computed, fuel_type, transmission, color, condition, location, availability, price, vehicle_type, lkw_type, machine_type, body_type, operating_hours, operating_hours_unit, mileage_km, description, timestamps, deleted_at soft-delete)
-- MobileDeListing model: vehicle_id FK, ad_id, sync_status, synced_at, error_log
-- 7 API endpoints: GET /vehicles (list+filter+sort+paginate), POST /vehicles (create), GET /vehicles/:id (detail), PUT /vehicles/:id (update), DELETE /vehicles/:id (soft-delete), POST /vehicles/:id/mobile-de/push (202 async), GET /vehicles/:id/mobile-de/status
-- mobile.de service: push_listing, update_listing, delete_listing, get_listing_status, retry_failed_listing (max 3 retries)
-- Field mapping: map_fields() converts Vehicle to mobile.de Ad format (vin, firstRegistration YYYY-MM, mileage, price EUR, power, category, bodyType, sellerLocation)
-- All endpoints require JWT Bearer auth
-- Config: MOBILE_DE_API_KEY, MOBILE_DE_SELLER_ID env vars added
+- Contact model: UUID PK, company_name, legal_form, address fields, address_country (ISO 3166-1 alpha-2), vat_id, phone, email, website, role (kaeufer/verkaeufer/beide), vat_id_status, is_private, timestamps, deleted_at soft-delete
+- ContactPerson model: UUID PK, contact_id FK CASCADE, name, function, phone, email, created_at
+- 7 API endpoints: GET /contacts (list+search+filter+sort+paginate), POST /contacts (create), GET /contacts/:id (detail+persons), PUT /contacts/:id (update), DELETE /contacts/:id (soft-delete), POST /contacts/:id/persons (add person), DELETE /contacts/:id/persons/:pid (remove person)
+- Contact service: list_contacts (search, role filter with beide inclusion, is_eu filter, is_private filter, sort, pagination), get_contact_by_id, create_contact (with nested persons), update_contact, soft_delete_contact, add_contact_person, remove_contact_person
+- USt-IdNr. validation: DE + 10 EU countries regex patterns, EU fallback, validate_vat_id, validate_vat_id_or_raise, get_country_code_from_vat_id
+- RBAC: all roles read, admin+verkaeufer write (require_role dependency)
+- Contacts router registered in main.py
 
 ## Frontend (COMPLETED)
-- VehicleList: Table with filters (search, type, availability, sort), pagination, error handling
-- VehicleForm: Create/edit form with validation (make, model, fin=17 chars, price>0, vehicle_type), conditional fields
-- VehicleDetail: All vehicle fields display, delete button, MobileDeStatus embedded
-- MobileDeStatus: Sync status badge, push button, ad_id, synced_at, error_log display
-- 3 pages: fahrzeuge list, fahrzeuge/neu create, fahrzeuge/[id] detail
+- ContactList: Table with filters (search, role, EU/Inland, sort), pagination, error handling, loading state
+- ContactForm: Create/edit form with USt-IdNr. validation, EU/Inland toggle (radio), country selector, role selector, legal form, address fields, contact info, is_private checkbox
+- ContactDetail: All contact fields display, delete button, contact persons section with add/remove via Modal
+- 3 pages: kontakte list, kontakte/neu create, kontakte/[id] detail
+- lib/contacts.ts: Full API client with typed interfaces + validateVatIdFormat frontend validation
 
 ## Test Evidence
-- Backend: 73/73 pytest passed, 82% total coverage (vehicle_service 99%, mobilede_service 80%, router 60%)
-- Frontend: 16/16 vitest passed
+- Backend: 73/73 pytest passed, 91% coverage on contact modules (service 99%, ust_validation 94%, models 93%, schemas 94%, router 67%)
+- Frontend: 20/20 vitest passed
 - test_report.md updated with full results
-- All mobile.de HTTP calls mocked in tests, no real API calls
-- Soft-delete verified: deleted_at set, vehicle excluded from list and detail queries
+- All acceptance criteria verified and documented