feat: Fase 1 – Fondamenta complete (backend FastAPI + auth + permessi)

- docker-compose.yml: PostgreSQL 16, Redis 7, MinIO, Nginx
- backend FastAPI: struttura monorepo, config pydantic-settings
- modelli SQLAlchemy: tutti i modelli (tenants, users, mailboxes, messages, archival, permissions, labels, audit_log)
- migrazione Alembic 0001: schema completo in pure SQL
- auth API: login JWT, refresh token rotation, logout, 2FA TOTP (setup/verify/disable)
- CRUD utenti: lista, crea, modifica, reset password, soft delete
- permessi granulari (Fase 1-A): mailbox_permissions, assegna/revoca/lista
- CRUD tenant: gestione super-admin
- sicurezza: AES-256-GCM cifratura credenziali IMAP/SMTP, bcrypt password
- RLS PostgreSQL: isolamento multi-tenant per request
- seed sviluppo: tenant demo + admin + operator
- test unit: security (bcrypt, JWT, AES), auth_service
- test integration: auth endpoints, users endpoints
- CI GitHub Actions: lint (ruff), test (pytest), build Docker, security scan
- infra: nginx.conf, redis.conf
- Makefile con comandi make dev/test/migrate/seed

Definition of Done:
✅ Login, refresh token e TOTP funzionanti
✅ make dev porta in piedi tutto lo stack locale
✅ CI configurata

backend/app/api/v1/users.py

@@ -0,0 +1,147 @@
+"""
+Router utenti – CRUD per admin del tenant.
+
+Endpoint:
+  GET    /api/v1/users              → lista utenti (admin)
+  POST   /api/v1/users              → crea utente (admin)
+  GET    /api/v1/users/{id}         → dettaglio utente (admin)
+  PATCH  /api/v1/users/{id}         → modifica utente (admin)
+  DELETE /api/v1/users/{id}         → disabilita utente (admin)
+  POST   /api/v1/users/{id}/reset-password → reset password (admin)
+"""
+
+import uuid
+
+from fastapi import APIRouter, Query
+
+from app.dependencies import AdminUser, DB
+from app.schemas.user import (
+    UserCreateRequest,
+    UserListResponse,
+    UserPasswordResetRequest,
+    UserResponse,
+    UserUpdateRequest,
+)
+from app.services.user_service import UserService
+
+router = APIRouter(prefix="/users", tags=["Utenti"])
+
+
+@router.get(
+    "",
+    response_model=UserListResponse,
+    summary="Lista utenti del tenant",
+)
+async def list_users(
+    current_user: AdminUser,
+    db: DB,
+    page: int = Query(default=1, ge=1),
+    page_size: int = Query(default=25, ge=1, le=100),
+) -> UserListResponse:
+    service = UserService(db)
+    users, total = await service.list_users(
+        tenant_id=current_user.tenant_id,
+        page=page,
+        page_size=page_size,
+    )
+    import math
+    return UserListResponse(
+        items=[UserResponse.model_validate(u) for u in users],
+        total=total,
+        page=page,
+        page_size=page_size,
+        pages=math.ceil(total / page_size) if page_size else 0,
+    )
+
+
+@router.post(
+    "",
+    response_model=UserResponse,
+    status_code=201,
+    summary="Crea nuovo utente nel tenant",
+)
+async def create_user(
+    body: UserCreateRequest,
+    current_user: AdminUser,
+    db: DB,
+) -> UserResponse:
+    service = UserService(db)
+    user = await service.create_user(
+        tenant_id=current_user.tenant_id,
+        data=body,
+        created_by=current_user,
+    )
+    return UserResponse.model_validate(user)
+
+
+@router.get(
+    "/{user_id}",
+    response_model=UserResponse,
+    summary="Dettaglio utente",
+)
+async def get_user(
+    user_id: uuid.UUID,
+    current_user: AdminUser,
+    db: DB,
+) -> UserResponse:
+    service = UserService(db)
+    user = await service.get_user(user_id, current_user.tenant_id)
+    return UserResponse.model_validate(user)
+
+
+@router.patch(
+    "/{user_id}",
+    response_model=UserResponse,
+    summary="Modifica utente",
+)
+async def update_user(
+    user_id: uuid.UUID,
+    body: UserUpdateRequest,
+    current_user: AdminUser,
+    db: DB,
+) -> UserResponse:
+    service = UserService(db)
+    user = await service.update_user(
+        user_id=user_id,
+        tenant_id=current_user.tenant_id,
+        data=body,
+        updated_by=current_user,
+    )
+    return UserResponse.model_validate(user)
+
+
+@router.delete(
+    "/{user_id}",
+    status_code=204,
+    summary="Disabilita utente (soft delete)",
+)
+async def delete_user(
+    user_id: uuid.UUID,
+    current_user: AdminUser,
+    db: DB,
+) -> None:
+    service = UserService(db)
+    await service.delete_user(
+        user_id=user_id,
+        tenant_id=current_user.tenant_id,
+        deleted_by=current_user,
+    )
+
+
+@router.post(
+    "/{user_id}/reset-password",
+    status_code=204,
+    summary="Reset password utente (admin)",
+)
+async def reset_password(
+    user_id: uuid.UUID,
+    body: UserPasswordResetRequest,
+    current_user: AdminUser,
+    db: DB,
+) -> None:
+    service = UserService(db)
+    await service.reset_password(
+        user_id=user_id,
+        tenant_id=current_user.tenant_id,
+        new_password=body.new_password,
+    )