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/scripts/format.sh

@@ -1,5 +1,5 @@
 #!/bin/sh -e
 set -x
 
-ruff check app scripts --fix
-ruff format app scripts
+ruff check fluksio scripts --fix
+ruff format fluksio scripts