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/fluksio/flow/nodes/__init__.py

@@ -0,0 +1,37 @@
+"""Built-in node types.
+
+Split by the outside world each one talks to. Importing from
+``fluksio.flow.nodes`` keeps working, which is what every caller does.
+"""
+
+from fluksio.flow.nodes.base import RESERVED_SETTINGS, Node
+from fluksio.flow.nodes.delay import DelayNode
+from fluksio.flow.nodes.exec import ExecNode
+from fluksio.flow.nodes.file import FileNode
+from fluksio.flow.nodes.http import HttpNode
+from fluksio.flow.nodes.influx import InfluxDbNode
+from fluksio.flow.nodes.inject import InjectNode
+from fluksio.flow.nodes.logic import ChangeNode, JoinNode, RbeNode, SwitchNode
+from fluksio.flow.nodes.mlp import MLPNode
+from fluksio.flow.nodes.mqtt import MqttNode
+from fluksio.flow.nodes.ntfy import NtfyNode
+from fluksio.flow.nodes.trigger import TriggerNode
+
+__all__ = [
+    "ChangeNode",
+    "DelayNode",
+    "ExecNode",
+    "FileNode",
+    "HttpNode",
+    "InfluxDbNode",
+    "InjectNode",
+    "JoinNode",
+    "MLPNode",
+    "MqttNode",
+    "Node",
+    "NtfyNode",
+    "RESERVED_SETTINGS",
+    "RbeNode",
+    "SwitchNode",
+    "TriggerNode",
+]