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/Dockerfile

@@ -25,20 +25,20 @@ ENV PATH="/app/.venv/bin:$PATH"
 RUN --mount=type=cache,target=/root/.cache/uv \
     --mount=type=bind,source=uv.lock,target=uv.lock \
     --mount=type=bind,source=pyproject.toml,target=pyproject.toml \
-    uv sync --frozen --no-install-workspace --package app
+    uv sync --frozen --no-install-workspace --package fluksio
 
 COPY ./backend/scripts /app/backend/scripts
 
 COPY ./backend/pyproject.toml ./backend/alembic.ini /app/backend/
 
-COPY ./backend/app /app/backend/app
+COPY ./backend/fluksio /app/backend/fluksio
 
 # Sync the project
 # Ref: https://docs.astral.sh/uv/guides/integration/docker/#intermediate-layers
 RUN --mount=type=cache,target=/root/.cache/uv \
     --mount=type=bind,source=uv.lock,target=uv.lock \
     --mount=type=bind,source=pyproject.toml,target=pyproject.toml \
-    uv sync --frozen --package app
+    uv sync --frozen --package fluksio
 
 # Connectors are ordinary installed packages found through the
 # `fluksio.node_types` entry point. `make connectors` builds them into here;
@@ -54,4 +54,4 @@ WORKDIR /app/backend/
 # Single worker on purpose: the process hosts the flow engine, and a second
 # worker would be a second engine — duplicated subscriptions, cron ticks and
 # webhooks. Scaling out is the M5 worker split, not more uvicorn processes.
-CMD ["fastapi", "run", "app/main.py"]
+CMD ["fastapi", "run", "fluksio/main.py"]