feat: add vLLM/local LLM support

- Add vllm provider configuration in config schema
- Auto-detect vLLM endpoints and use hosted_vllm/ prefix for LiteLLM
- Pass api_base directly to acompletion for custom endpoints
- Add vLLM status display in CLI status command
- Add vLLM setup documentation in README

README.md

@@ -116,6 +116,43 @@ nanobot agent -m "What is 2+2?"
 
 That's it! You have a working AI assistant in 2 minutes.
 
+## 🖥️ Local Models (vLLM)
+
+Run nanobot with your own local models using vLLM or any OpenAI-compatible server.
+
+**1. Start your vLLM server**
+
+```bash
+vllm serve meta-llama/Llama-3.1-8B-Instruct --port 8000
+```
+
+**2. Configure** (`~/.nanobot/config.json`)
+
+```json
+{
+  "providers": {
+    "vllm": {
+      "apiKey": "dummy",
+      "apiBase": "http://localhost:8000/v1"
+    }
+  },
+  "agents": {
+    "defaults": {
+      "model": "meta-llama/Llama-3.1-8B-Instruct"
+    }
+  }
+}
+```
+
+**3. Chat**
+
+```bash
+nanobot agent -m "Hello from my local LLM!"
+```
+
+> [!TIP]
+> The `apiKey` can be any non-empty string for local servers that don't require authentication.
+
 ## 💬 Chat Apps
 
 Talk to your nanobot through Telegram or WhatsApp — anytime, anywhere.