feat: authentication — register, login, JWT, tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/auth.py

@@ -0,0 +1,38 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.database import get_db
+from app.schemas.user import Token, UserCreate, UserLogin, UserResponse
+from app.services.auth import (
+    create_access_token,
+    create_user,
+    get_user_by_username,
+    verify_password,
+)
+from app.api.deps import get_current_user
+from app.models.user import User
+
+router = APIRouter(prefix="/api/auth", tags=["auth"])
+
+
+@router.post("/register", response_model=UserResponse, status_code=201)
+async def register(data: UserCreate, db: AsyncSession = Depends(get_db)):
+    existing = await get_user_by_username(db, data.username)
+    if existing:
+        raise HTTPException(status_code=400, detail="Username already taken")
+    user = await create_user(db, data.username, data.email, data.password)
+    return user
+
+
+@router.post("/login", response_model=Token)
+async def login(data: UserLogin, db: AsyncSession = Depends(get_db)):
+    user = await get_user_by_username(db, data.username)
+    if not user or not verify_password(data.password, user.password_hash):
+        raise HTTPException(status_code=401, detail="Invalid credentials")
+    token = create_access_token(str(user.id))
+    return Token(access_token=token)
+
+
+@router.get("/me", response_model=UserResponse)
+async def me(user: User = Depends(get_current_user)):
+    return user