fix: add OpenEnv environment manifest

Add root openenv.yaml required by OpenEnv validator and provide server.app:app entrypoint shim for importable app resolution from repo root.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

openenv.yaml

@@ -0,0 +1,6 @@
+spec_version: 1
+name: scraperl
+type: space
+runtime: fastapi
+app: server.app:app
+port: 7860

server/__init__.py

@@ -0,0 +1,2 @@
+"""OpenEnv entrypoint package."""
+

server/app.py

@@ -0,0 +1,13 @@
+"""OpenEnv-compatible FastAPI app export."""
+
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+BACKEND_DIR = Path(__file__).resolve().parents[1] / "backend"
+if str(BACKEND_DIR) not in sys.path:
+    sys.path.insert(0, str(BACKEND_DIR))
+
+from app.main import app  # noqa: E402,F401
+