build.sh: skip --env-file when env file does not exist

docker run fails hard if the path passed to --env-file is missing.
Make the flag conditional so apps without an env file (or where the
file hasn't been created yet) still start successfully.

https://claude.ai/code/session_01FKCW3FDjNFj6jve4niMFXH

builder/build.sh

@@ -90,10 +90,16 @@ fi
 
 # ── 5. Start new container ────────────────────────────────────────────────────
 log "Starting container ${CONTAINER_NAME}…"
+ENV_FILE_ARG=()
+if [ -n "${ENV_FILE:-}" ] && [ -f "$ENV_FILE" ]; then
+    ENV_FILE_ARG=(--env-file "$ENV_FILE")
+else
+    log "No env file found at '${ENV_FILE:-}'; starting without one."
+fi
 docker run --detach \
     --name "$CONTAINER_NAME" \
     --network hiy-net \
-    --env-file "$ENV_FILE" \
+    "${ENV_FILE_ARG[@]}" \
     --expose "$PORT" \
     --label "hiy.app=${APP_ID}" \
     --label "hiy.port=${PORT}" \