Throw ToolError on Playwright goto failure

Replace returning an error object with throwing a ToolError when Playwright goto fails in ComputerTool. This standardizes error handling so callers can catch exceptions and preserves the original response error or falls back to 'Playwright goto failed'.

Author: dprevoznik

pkg/templates/typescript/yutori-computer-use/tools/computer.ts

@@ -306,7 +306,7 @@ export class ComputerTool {
         timeout_sec: 60,
       });
       if (!response.success) {
-        return { error: response.error ?? 'Playwright goto failed' };
+        throw new ToolError(response.error ?? 'Playwright goto failed');
       }
       await this.sleep(ACTION_DELAY_MS);
       return this.screenshot();