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_provenance.py

@@ -5,19 +5,19 @@ actually published, it pulses all of them — and when the cause is a dashboard
 control or another flow, it pulses a node that did nothing at all.
 """
 
-from app.flow.dashboards import (
+from fluksio.flow.dashboards import (
     DashboardDef,
     DashboardStore,
     PageDef,
     SectionDef,
     WidgetDef,
 )
-from app.flow.events import EventBus
-from app.flow.messages import DType, MessageSpec
-from app.flow.nodes import Node
-from app.flow.pipeline import Pipeline, ValueSource
-from app.flow.state import MemoryState
-from app.flow.store import FlowStore
+from fluksio.flow.events import EventBus
+from fluksio.flow.messages import DType, MessageSpec
+from fluksio.flow.nodes import Node
+from fluksio.flow.pipeline import Pipeline, ValueSource
+from fluksio.flow.state import MemoryState
+from fluksio.flow.store import FlowStore
 
 
 def collect(bus: EventBus) -> list[dict]: