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/mcp/test_mcp_http.py

@@ -10,9 +10,9 @@ import httpx
 import pytest
 from fastapi.testclient import TestClient
 
-from app.core import security
-from app.core.config import settings
-from app.main import app
+from fluksio.core import security
+from fluksio.core.config import settings
+from fluksio.main import app
 
 MCP_HEADERS = {"Accept": "application/json, text/event-stream"}
 
@@ -31,8 +31,8 @@ def over_mcp(monkeypatch: pytest.MonkeyPatch):
     whole exchange happens inside a single ``asyncio.run``.
     """
     monkeypatch.setattr(settings, "MCP_ENABLED", True)
-    from app.mcp import http as mcp_http
-    from app.mcp import server as mcp_server
+    from fluksio.mcp import http as mcp_http
+    from fluksio.mcp import server as mcp_server
 
     # A FastMCP instance enters its session manager once, and another test in
     # the run may have built one already.