Rename the import package app to fluksio

A wheel whose top-level module is `app` collides with anything else in a
user's venv, so the package that is about to be published takes the name
it is published under. Only the Python package moves; the repo, the
Docker WORKDIR and the compose project keep theirs.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

backend/tests/conftest.py

@@ -10,11 +10,11 @@ from sqlalchemy import create_engine, text
 from sqlalchemy.engine import make_url
 from sqlmodel import Session, SQLModel, select
 
-from app.cloud import config as cloud_config
-from app.core.config import settings
-from app.core.db import engine, init_db
-from app.main import app
-from app.models import User
+from fluksio.cloud import config as cloud_config
+from fluksio.core.config import settings
+from fluksio.core.db import engine, init_db
+from fluksio.main import app
+from fluksio.models import User
 from tests.utils.portal import INSTALLATION_ID, ISSUER, jwks
 from tests.utils.user import authentication_token_from_email
 from tests.utils.utils import get_superuser_token_headers