Add Polaris FastAPI backend: models/schemas, pricing+scoring+order router, importer, Celery tasks, API routers, seed script

backend/app/routers/health.py

@@ -0,0 +1,23 @@
+"""GET /api/health -> {status, version}"""
+from fastapi import APIRouter, Depends
+from sqlalchemy import text
+from sqlalchemy.orm import Session
+
+from app.database import get_db
+from app.version import VERSION
+
+router = APIRouter()
+
+
+@router.get("/health")
+def health(db: Session = Depends(get_db)):
+    db_status = "ok"
+    try:
+        db.execute(text("SELECT 1"))
+    except Exception:  # noqa: BLE001
+        db_status = "error"
+    return {
+        "status": "ok" if db_status == "ok" else "degraded",
+        "version": VERSION,
+        "db": db_status,
+    }