Added the sqlite3 database

backend/app/routers/proposal.py

@@ -0,0 +1,11 @@
+from fastapi import APIRouter
+from typing import List, Optional
+from app.data.data import proposals
+from app.models import Proposal  # Import the Address model
+
+
+router = APIRouter()
+
+@router.get("/", response_model=List[Proposal])
+async def get_proposals():
+    return proposals