flake: check for existance of python project

flake.nix

@@ -36,6 +36,16 @@
                         source .env
                         set +a
                     fi
+
+                    if [ ! -d .venv ]; then
+                        echo "Creating Python virtual environment in .venv"
+                        python3 -m venv .venv
+                    fi
+
+                    if compgen -G "app/*.py" > /dev/null; then
+                        .venv/bin/pip install -r ./app/requirements.txt
+                        source .venv/bin/activate
+                    fi
                 '';
             };
         });