refactor: improve code structure and optimize key functions

backend/app/api/v1/auth.py

@@ -0,0 +1,32 @@
+from datetime import timedelta
+
+from fastapi import APIRouter, HTTPException, status
+from pydantic import BaseModel, Field
+
+from app.core.config import settings
+from app.core.security import create_access_token
+from app.schemas.user import Token
+
+
+class LoginRequest(BaseModel):
+    username: str = Field(min_length=1)
+    password: str = Field(min_length=1)
+
+
+router = APIRouter()
+
+
+@router.post("/login", response_model=Token)
+async def login_for_access_token(payload: LoginRequest) -> Token:
+    if not (payload.username == "admin" and payload.password == "admin"):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+        )
+
+    access_token = create_access_token(
+        subject="00000000-0000-0000-0000-000000000001",
+        role="PM",
+        expires_delta=timedelta(minutes=settings.JWT_EXPIRE_MINUTES),
+    )
+    return Token(access_token=access_token, token_type="bearer")