When GSD hits a blocking decision point (AskUserQuestion, next action prompt),
external watchers have no way to detect it. Users monitoring multiple auto
sessions must visually check each terminal.
Added:
- state signal-waiting: writes .planning/WAITING.json (or .gsd/WAITING.json)
with type, question, options, timestamp, and phase info
- state signal-resume: removes WAITING.json when user answers
Signal file format:
{ status, type, question, options[], since, phase }
External tools can watch for this file via fswatch, polling, or inotify.
Complements the existing remote-questions extension (Slack/Discord).
Fixes#1034
7dd31e6d20