feat: backend project setup with FastAPI structure and dependencies

- Create directory structure per IMPLEMENTATION_PLAN.md Section 12
- Add requirements.txt with FastAPI, SQLAlchemy, CrewAI, etc.
- Add core/config.py for environment variable configuration
- Add core/database.py for SQLite connection
- Add core/security.py for password hashing and JWT
- Add FastAPI app entry point (main.py) with all API routers
- Add Uvicorn runner (run.py)
- Add API route stubs (auth, bots, backtest, simulate, config)
- Add db/models.py with SQLAlchemy models
- Add db/schemas.py with Pydantic schemas
- Add service stubs (ai_agent, backtest, simulate engines)
- Add .env.example with all required environment variables
- Verify server starts correctly

src/backend/app/api/auth.py

@@ -0,0 +1,52 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
+from sqlalchemy.orm import Session
+from datetime import timedelta
+from typing import Annotated
+
+from ..core.database import get_db
+from ..core.security import (
+    get_password_hash,
+    verify_password,
+    create_access_token,
+    verify_token,
+)
+from ..core.config import get_settings
+from ..db.schemas import UserCreate, UserResponse, Token
+
+router = APIRouter()
+settings = get_settings()
+oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/token")
+
+
+@router.post("/register", response_model=UserResponse)
+def register(user: UserCreate, db: Session = Depends(get_db)):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.post("/login")
+def login(
+    form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
+    db: Session = Depends(get_db),
+):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.post("/logout")
+def logout(token: Annotated[str, Depends(oauth2_scheme)]):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.get("/me", response_model=UserResponse)
+def get_me(
+    token: Annotated[str, Depends(oauth2_scheme)], db: Session = Depends(get_db)
+):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )