Add initial project documentation

docs/services/orchestion-service.md

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+# Orchestration Service
+
+**Package:** `@nexusai/orchestration-service`  
+**Location:** `packages/orchestration-service`  
+**Deployed on:** Mini PC 2 (192.168.0.205)  
+**Port:** 4000
+
+## Purpose
+
+The main entry point for all clients. Assembles context packages from
+memory, routes prompts to inference, and writes new episodes back to
+memory after each interaction.
+
+## Dependencies
+
+- `express` — HTTP API
+- `node-fetch` — inter-service HTTP communication
+- `dotenv` — environment variable loading
+- `@nexusai/shared` — shared utilities
+
+## Environment Variables
+
+| Variable | Required | Default | Description |
+|---|---|---|---|
+| PORT | No | 4000 | Port to listen on |
+| MEMORY_SERVICE_URL | No | http://localhost:3002 | Memory service URL |
+| EMBEDDING_SERVICE_URL | No | http://localhost:3003 | Embedding service URL |
+| INFERENCE_SERVICE_URL | No | http://localhost:3001 | Inference service URL |
+
+## Endpoints
+
+| Method | Path | Description |
+|---|---|---|
+| GET | /health | Service health check |
+
+> Further endpoints will be documented as the service is built out.