feat(gateway): add config toggle for chat completions endpoint

docs/gateway/configuration.md

@@ -1803,6 +1803,7 @@ Related docs:
 Notes:
 - `clawdbot gateway` refuses to start unless `gateway.mode` is set to `local` (or you pass the override flag).
 - `gateway.port` controls the single multiplexed port used for WebSocket + HTTP (control UI, hooks, A2UI).
+- Disable the OpenAI-compatible endpoint with `gateway.http.endpoints.chatCompletions.enabled: false`.
 - Precedence: `--port` > `CLAWDBOT_GATEWAY_PORT` > `gateway.port` > default `18789`.
 - Non-loopback binds (`lan`/`tailnet`/`auto`) require auth. Use `gateway.auth.token` (or `CLAWDBOT_GATEWAY_TOKEN`).
 - `gateway.remote.token` is **only** for remote CLI calls; it does not enable local gateway auth. `gateway.token` is ignored.

docs/gateway/openai-http-api.md

@@ -36,6 +36,22 @@ Or target a specific Clawdbot agent by header:
 Advanced:
 - `x-clawdbot-session-key: <sessionKey>` to fully control session routing.
 
+## Disabling the endpoint
+
+Set `gateway.http.endpoints.chatCompletions.enabled` to `false`:
+
+```json5
+{
+  gateway: {
+    http: {
+      endpoints: {
+        chatCompletions: { enabled: false }
+      }
+    }
+  }
+}
+```
+
 ## Session behavior
 
 By default the endpoint is **stateless per request** (a new session key is generated each call).