Update app.py

app.py

@@ -1,8 +1,16 @@
 import sys
 from pathlib import Path
 
-REPO_ROOT = Path(__file__).resolve().parent.parent
-BACKEND_PATH = str(REPO_ROOT / "backend")
+
+def _find_backend_path() -> Path:
+    current = Path(__file__).resolve().parent
+    for parent in [current] + list(current.parents):
+        candidate = parent / "backend"
+        if candidate.is_dir():
+            return candidate
+    raise RuntimeError("Could not find backend directory in parent paths")
+
+BACKEND_PATH = str(_find_backend_path())
 if BACKEND_PATH not in sys.path:
     sys.path.insert(0, BACKEND_PATH)