fix: enforce strict config validation

extensions/google-antigravity-auth/index.ts

@@ -1,6 +1,7 @@
 import { createHash, randomBytes } from "node:crypto";
 import { readFileSync } from "node:fs";
 import { createServer } from "node:http";
+import { emptyPluginConfigSchema } from "clawdbot/plugin-sdk";
 
 // OAuth constants - decoded from pi-ai's base64 encoded values to stay in sync
 const decode = (s: string) => Buffer.from(s, "base64").toString();
@@ -360,6 +361,7 @@ const antigravityPlugin = {
   id: "google-antigravity-auth",
   name: "Google Antigravity Auth",
   description: "OAuth flow for Google Antigravity (Cloud Code Assist)",
+  configSchema: emptyPluginConfigSchema(),
   register(api) {
     api.registerProvider({
       id: "google-antigravity",