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/db/schemas.py

@@ -0,0 +1,93 @@
+from pydantic import BaseModel, EmailStr
+from typing import Optional, List, Any
+from datetime import datetime
+
+
+class UserCreate(BaseModel):
+    email: EmailStr
+    password: str
+
+
+class UserResponse(BaseModel):
+    id: str
+    email: str
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str
+
+
+class BotCreate(BaseModel):
+    name: str
+    description: Optional[str] = None
+    strategy_config: dict
+    llm_config: dict
+
+
+class BotUpdate(BaseModel):
+    name: Optional[str] = None
+    description: Optional[str] = None
+    strategy_config: Optional[dict] = None
+    llm_config: Optional[dict] = None
+    status: Optional[str] = None
+
+
+class BotResponse(BaseModel):
+    id: str
+    user_id: str
+    name: str
+    description: Optional[str]
+    strategy_config: dict
+    llm_config: dict
+    status: str
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class BacktestCreate(BaseModel):
+    token: str
+    chain: str
+    timeframe: str
+    start_date: str
+    end_date: str
+
+
+class BacktestResponse(BaseModel):
+    id: str
+    bot_id: str
+    started_at: datetime
+    ended_at: Optional[datetime]
+    status: str
+    config: dict
+    result: Optional[dict]
+
+    class Config:
+        from_attributes = True
+
+
+class SimulationCreate(BaseModel):
+    token: str
+    chain: str
+    duration_seconds: int = 3600
+    auto_execute: bool = False
+
+
+class SimulationResponse(BaseModel):
+    id: str
+    bot_id: str
+    started_at: datetime
+    status: str
+    config: dict
+    signals: Optional[List[dict]]
+
+    class Config:
+        from_attributes = True