feat(cli): add http.apps field for mounting multiple HTTP apps at path prefixes

Add support for the http.apps config field in langgraph.json that lets
users mount multiple HTTP apps at different path prefixes alongside the
built-in LangGraph API.

Config format:
  {
    "http": {
      "app": "./custom_routes.py:app",
      "apps": {
        "/dashboard": "./dashboard.py:app",
        "/ext": "./extension.js:app",
        "/conduit": "some-npm-package:app"
      }
    }
  }

Changes:
- Add apps: dict[str, str] | None to HttpConfig TypedDict in schemas.py
- Add validation for http.apps entries (prefix must start with /, values
  must be module:attribute format)
- Add _update_http_apps_paths() for Docker container path rewriting
- Add _is_js_http_app() and _has_js_http_apps() helpers for JS detection
- Ensure Node.js is installed in Docker images when JS HTTP apps present
- Regenerate JSON schema files

Co-authored-by: Christian Bromann <christian-bromann@users.noreply.github.com>

libs/cli/langgraph_cli/schemas.py

@@ -446,6 +446,25 @@ class HttpConfig(TypedDict, total=False):
     Format: "path/to/module.py:app_var"
     If provided, it can override or extend the default routes.
     """
+    apps: dict[str, str] | None
+    """Optional. Record mapping path prefix to app module path.
+
+    Each key is a URL path prefix (e.g., "/dashboard"), and each value is an
+    import path in "file:export" format (e.g., "./dashboard.py:app").
+
+    Python apps (.py) are mounted in-process as FastAPI/Starlette sub-applications.
+    JS apps (.js, .ts, .mts, .mjs) are spawned as Node.js subprocess servers
+    with a reverse proxy forwarding requests from the main server.
+    npm package references (paths not starting with . or /) are resolved as
+    npm imports in the JS subprocess.
+
+    Example:
+        {
+            "/dashboard": "./dashboard.py:app",
+            "/ext": "./extension.js:app",
+            "/conduit": "some-npm-package:app"
+        }
+    """
     disable_assistants: bool
     """Optional. If `True`, /assistants routes are removed from the server.