fix: bootstrap node deps for gradio runtime

app.py

@@ -62,6 +62,29 @@ def verify_api_key(x_api_key: Optional[str] = Header(None)):
 
 MAX_CONCURRENT_ZIWEI = int(os.environ.get("ZIWEI_MAX_CONCURRENT", "2"))
 _ziwei_subprocess_slots = threading.BoundedSemaphore(MAX_CONCURRENT_ZIWEI)
+_node_dependency_lock = threading.Lock()
+
+
+def ensure_node_dependencies() -> None:
+    """Install Node dependencies on runtimes that do not run Docker build steps."""
+    if os.path.isdir("node_modules/iztro"):
+        return
+
+    with _node_dependency_lock:
+        if os.path.isdir("node_modules/iztro"):
+            return
+
+        result = subprocess.run(
+            ["npm", "install", "--production"],
+            capture_output=True,
+            text=True,
+            timeout=180
+        )
+        if result.returncode != 0:
+            raise HTTPException(
+                status_code=500,
+                detail=f"Node dependency installation failed: {result.stderr or result.stdout}"
+            )
 
 
 class ZiweiRequest(BaseModel):
@@ -80,6 +103,8 @@ def run_ziwei_calculation(request: BaseModel) -> Dict[str, Any]:
     统一处理subprocess调用、returncode检查和JSON解析,
     失败时直接抛出HTTPException。
     """
+    ensure_node_dependencies()
+
     input_data = {
         "birth_date": request.birth_date,
         "birth_time": request.birth_time,