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/setup.py

@@ -0,0 +1,20 @@
+from setuptools import setup, find_packages
+
+setup(
+    name="randebu-backend",
+    version="0.1.0",
+    packages=find_packages(),
+    install_requires=[
+        "fastapi>=0.109.0",
+        "uvicorn>=0.27.0",
+        "sqlalchemy>=2.0.0",
+        "pydantic>=2.5.0",
+        "pydantic-settings>=2.1.0",
+        "python-jose[cryptography]>=3.3.0",
+        "passlib[bcrypt]>=1.7.4",
+        "crewai>=0.1.0",
+        "anthropic>=0.18.0",
+        "httpx>=0.26.0",
+        "python-multipart>=0.0.6",
+    ],
+)