⚡ Live Playground: AI Dev Tool: Launch HN ProvenMetal YC

```python
# AI Dev Tool: FastAPI + Supabase Production Starter Boilerplate
# Description: A high-demand production-ready developer code asset for building scalable web applications
# Category: Production Starter Boilerplate

from fastapi import FastAPI, Depends, HTTPException
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from pydantic import BaseModel
from supabase import create_client, Client
from typing import Optional

# Initialize Supabase client
SUPABASE_URL = "https://your-supabase-url.supabase.co"
SUPABASE_KEY = "your-supabase-key"
SUPABASE_SECRET = "your-supabase-secret"
supabase: Client = create_client(SUPABASE_URL, SUPABASE_KEY)

# Initialize FastAPI app
app = FastAPI()

# OAuth2 scheme
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

# User model
class User(BaseModel):
    id: int
    username: str
    email: str

# Token model
class Token(BaseModel):
    access_token: str
    token_type: str

# Authenticate user
async def authenticate_user(username: str, password: str):
    """
    Authenticate user using Supabase auth API
⚡ Live Code Sandbox: AI Dev Tool: Launch HN ProvenMetal YC
