T02: companies + contacts + import/export + N:M + soft-delete + GDPR + FTS

- Company CRUD with soft-delete, FTS search (tsvector + GIN), filter, pagination
- Contact CRUD with N:M company linking via company_contacts
- CSV/XLSX export, CSV import with dry-run preview
- GDPR hard-delete with deletion_log
- Audit log on all mutations
- 27 new tests (24 ACs), 56 total tests pass
- Migration 0002: contacts, company_contacts, FTS search_tsv
- Fixed T01 tests: POST→201, PATCH→PUT compatibility

app/models/__init__.py

@@ -8,9 +8,11 @@ from app.models.audit import AuditLog, DeletionLog
 from app.models.notification import Notification
 from app.models.auth import PasswordResetToken, ApiToken
 from app.models.company import Company
+from app.models.contact import Contact, CompanyContact
 
 __all__ = [
     "Tenant", "User", "UserTenant", "Role", "Session",
     "AuditLog", "DeletionLog", "Notification",
     "PasswordResetToken", "ApiToken", "Company",
+    "Contact", "CompanyContact",
 ]