Use single .env for local startup

scripts/start_dev.sh

@@ -3,4 +3,9 @@ set -euo pipefail
 
 cd "$(dirname "$0")/.."
 source .venv/bin/activate
-exec uvicorn app.main:app --env-file .env.development --host 127.0.0.1 --port 8000 --reload
+ENV_FILE=".env"
+if [ ! -f "$ENV_FILE" ]; then
+  echo "missing $ENV_FILE. copy .env.example to .env first."
+  exit 1
+fi
+exec uvicorn app.main:app --env-file "$ENV_FILE" --host 127.0.0.1 --port 8000 --reload