Added the sqlite3 database

backend/app/routers/contact.py

@@ -0,0 +1,26 @@
+# app/routers/contact.py
+from fastapi import APIRouter, HTTPException, status
+from typing import List
+from app.data.data import contacts
+from app.models import ContactPerson
+
+router = APIRouter()
+
+@router.get("/", response_model=List[ContactPerson])
+async def get_contacts():
+    return contacts
+
+@router.post("/", response_model=ContactPerson, status_code=status.HTTP_201_CREATED)
+async def create_contact(contact: ContactPerson):
+    if any(c.email == contact.email for c in contacts):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="This contact already exists."
+        )
+    if contacts:
+        max_id = max(c.id for c in contacts)
+        contact.id = max_id + 1 if contact.id is None else contact.id
+    else:
+        contact.id = 1 if contact.id is None else contact.id
+    contacts.append(contact)
+    return contact