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/flow/test_http_hook_secret.py

@@ -11,13 +11,13 @@ import pytest
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
 
-from app.flow.controller import HOOK_PREFIX, FlowController
-from app.flow.messages import DType, MessageSpec
-from app.flow.nodes import HttpNode
-from app.flow.pipeline import Pipeline
-from app.flow.schemas import FlowDef, NodeDef
-from app.flow.secrets import init_secrets, resolve_params
-from app.flow.store import FlowStore
+from fluksio.flow.controller import HOOK_PREFIX, FlowController
+from fluksio.flow.messages import DType, MessageSpec
+from fluksio.flow.nodes import HttpNode
+from fluksio.flow.pipeline import Pipeline
+from fluksio.flow.schemas import FlowDef, NodeDef
+from fluksio.flow.secrets import init_secrets, resolve_params
+from fluksio.flow.store import FlowStore
 
 SECRET = "d3vice-key"
 HOOK = f"{HOOK_PREFIX}/house/sensor"