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/backtest.py

@@ -0,0 +1,36 @@
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+from typing import List
+
+from ..core.database import get_db
+from ..db.schemas import BacktestCreate, BacktestResponse
+
+router = APIRouter()
+
+
+@router.post("/bots/{bot_id}/backtest", response_model=BacktestResponse)
+def start_backtest(bot_id: str, config: BacktestCreate, db: Session = Depends(get_db)):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.get("/bots/{bot_id}/backtest/{run_id}", response_model=BacktestResponse)
+def get_backtest(bot_id: str, run_id: str, db: Session = Depends(get_db)):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.get("/bots/{bot_id}/backtests", response_model=List[BacktestResponse])
+def list_backtests(bot_id: str, db: Session = Depends(get_db)):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )
+
+
+@router.post("/bots/{bot_id}/backtest/{run_id}/stop")
+def stop_backtest(bot_id: str, run_id: str, db: Session = Depends(get_db)):
+    raise HTTPException(
+        status_code=status.HTTP_501_NOT_IMPLEMENTED, detail="Not implemented"
+    )