feat: admin login, delete items, and IP bans API

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/main.py

@@ -3,6 +3,7 @@ from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
 
+from app.api.admin import router as admin_router
 from app.api.public import router as public_router
 from app.config import settings
 from app.db import Base, SessionLocal, engine
@@ -40,6 +41,7 @@ async def lifespan(_app: FastAPI):
 
 app = FastAPI(title="MincedPad", lifespan=lifespan)
 app.include_router(public_router)
+app.include_router(admin_router)
 
 
 @app.get("/api/health")