feat(extensions): add plan directory support to gemini-extension.json

packages/cli/src/config/extension-manager.ts

@@ -862,6 +862,7 @@ Would you like to attempt to install via "git clone" instead?`,
         installMetadata,
         mcpServers: config.mcpServers,
         excludeTools: config.excludeTools,
+        plan: config.plan,
         hooks,
         isActive: this.extensionEnablementManager.isEnabled(
           config.name,

packages/cli/src/config/extension.ts

@@ -28,6 +28,7 @@ export interface ExtensionConfig {
   contextFileName?: string | string[];
   excludeTools?: string[];
   settings?: ExtensionSetting[];
+  plan?: { directory?: string };
   /**
    * Custom themes contributed by this extension.
    * These themes will be registered when the extension is activated.