WIP checkpoint: Address review feedback: Scaffold FastAPI backend project structure

backend/app/routers/auth.py

@@ -3,6 +3,7 @@
 from datetime import datetime, timedelta, timezone
 
 from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordRequestForm
 from pydantic import BaseModel, EmailStr
 
 from jose import jwt
@@ -33,11 +34,6 @@ class RegisterRequest(BaseModel):
     password: str
 
 
-class LoginRequest(BaseModel):
-    username: str
-    password: str
-
-
 class UserResponse(BaseModel):
     id: int
     username: str
@@ -104,12 +100,16 @@ async def register(req: RegisterRequest, db: AsyncSession = Depends(get_db)):
 
 
 @router.post("/login", response_model=TokenResponse)
-async def login(req: LoginRequest, db: AsyncSession = Depends(get_db)):
-    """Authenticate user and return an access token."""
-    result = await db.execute(select(User).where(User.username == req.username))
+async def login(form: OAuth2PasswordRequestForm = Depends(), db: AsyncSession = Depends(get_db)):
+    """Authenticate user and return an access token.
+
+    Accepts form-encoded credentials (username/password) as expected by
+    OAuth2PasswordBearer, so the Swagger UI "Authorize" flow works correctly.
+    """
+    result = await db.execute(select(User).where(User.username == form.username))
     user = result.scalar_one_or_none()
 
-    if not user or not verify_password(req.password, user.hashed_password):
+    if not user or not verify_password(form.password, user.hashed_password):
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Incorrect username or password",