Docs: add Qwen Portal provider

docs/concepts/model-providers.md

@@ -183,6 +183,22 @@ Kimi Code uses a dedicated endpoint and key (separate from Moonshot):
 }
 ```
 
+### Qwen Portal OAuth (free tier)
+
+Qwen Portal provides OAuth access to Qwen Coder + Vision via a device-code flow.
+Enable the bundled plugin, then log in:
+
+```bash
+clawdbot plugins enable qwen-portal-auth
+clawdbot models auth login --provider qwen-portal --set-default
+```
+
+Model refs:
+- `qwen-portal/coder-model`
+- `qwen-portal/vision-model`
+
+See [/providers/qwen](/providers/qwen) for setup details and notes.
+
 ### Synthetic
 
 Synthetic provides Anthropic-compatible models behind the `synthetic` provider: