feat: bundle provider auth plugins

Co-authored-by: ItzR3NO <ItzR3NO@users.noreply.github.com>

extensions/google-gemini-cli-auth/README.md

@@ -0,0 +1,24 @@
+# Google Gemini CLI Auth (Clawdbot plugin)
+
+OAuth provider plugin for **Gemini CLI** (Google Code Assist).
+
+## Enable
+
+Bundled plugins are disabled by default. Enable this one:
+
+```bash
+clawdbot plugins enable google-gemini-cli-auth
+```
+
+Restart the Gateway after enabling.
+
+## Authenticate
+
+```bash
+clawdbot models auth login --provider google-gemini-cli --set-default
+```
+
+## Env vars
+
+- `CLAWDBOT_GEMINI_OAUTH_CLIENT_ID` / `GEMINI_CLI_OAUTH_CLIENT_ID`
+- `CLAWDBOT_GEMINI_OAUTH_CLIENT_SECRET` / `GEMINI_CLI_OAUTH_CLIENT_SECRET`