Add complete BlackRoad OS backend API and wire all apps

- Created FastAPI backend with all endpoints (auth, agents, chat, blockchain, payments)
- Added unified BlackRoad API client (blackroad-api.js) for all frontend apps
- Updated index.html to use new unified API
- Backend includes health checks, JWT auth, and mock AI responses
- Ready for Railway deployment with Procfile and railway.json
- All frontend apps can now share authentication and API calls

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/README.md

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+# BlackRoad OS Backend API
+
+Complete FastAPI backend for BlackRoad Operating System.
+
+## Features
+
+- **Authentication**: JWT-based auth with register/login
+- **AI Chat**: Conversation management with AI responses
+- **Agents**: Spawn, list, and manage 30,000+ AI agents
+- **Blockchain**: RoadChain transactions and blocks
+- **Payments**: Stripe checkout integration
+- **Files**: Cloud file management
+- **Social**: Social network feed
+
+## Local Development
+
+```bash
+# Install dependencies
+pip install -r requirements.txt
+
+# Run server
+uvicorn main:app --reload --port 8000
+
+# Test
+curl http://localhost:8000/health
+```
+
+## Railway Deployment
+
+```bash
+# From this directory
+railway login
+railway link
+railway up
+```
+
+## Environment Variables
+
+- `SECRET_KEY`: JWT secret (auto-generated if not set)
+- `STRIPE_SECRET_KEY`: Your Stripe secret key
+- `PORT`: Port to run on (default: 8000)
+
+## API Endpoints
+
+### Health
+- `GET /health` - Health check
+- `GET /ready` - Readiness check
+
+### Auth
+- `POST /api/auth/register` - Register new user
+- `POST /api/auth/login` - Login
+- `GET /api/auth/me` - Get current user
+
+### AI Chat
+- `POST /api/ai-chat/chat` - Send message
+- `GET /api/ai-chat/conversations` - List conversations
+
+### Agents
+- `POST /api/agents/spawn` - Spawn new agent
+- `GET /api/agents/list` - List agents
+- `GET /api/agents/{id}` - Get agent details
+- `DELETE /api/agents/{id}` - Terminate agent
+
+### Blockchain
+- `GET /api/blockchain/blocks` - Get blocks
+- `POST /api/blockchain/transaction` - Create transaction
+- `GET /api/blockchain/transactions` - Get transactions
+
+### Payments
+- `POST /api/payments/create-checkout-session` - Create Stripe checkout
+- `POST /api/payments/verify-payment` - Verify payment
+
+### Files
+- `GET /api/files/list` - List files
+
+### Social
+- `GET /api/social/feed` - Get social feed
+
+### System
+- `GET /api/system/stats` - System statistics
+
+## Architecture
+
+- FastAPI with async/await
+- JWT authentication
+- In-memory storage (replace with PostgreSQL/Redis in production)
+- CORS enabled for all origins
+- Mock AI responses (integrate with real LLM)
+
+## Production Considerations
+
+1. Replace in-memory storage with PostgreSQL
+2. Add Redis for sessions
+3. Integrate real LLM (OpenAI/Anthropic)
+4. Add rate limiting
+5. Enable HTTPS only
+6. Set strong SECRET_KEY
+7. Configure CORS for specific origins