Add Write to sidebar allowedTools (both sidebar-agent.ts and server.ts).
Write doesn't expand attack surface beyond what Bash already provides.
Replace empty stderr handler with buffer capture for better error
diagnostics. New bin/gstack-open-url for cross-platform URL opening.
Does NOT include Search Before Building intro flow (deferred).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Garry Tan