/next: what's the next step?

1. Gather state (read only what exists):
   • private notes (path in CLAUDE.local.md): planning/progress.md (Current state), planning/open-questions.md, ideas/inbox.md (Untriaged), backlog/README.md, planning/design-docs-plan.md (phases)
   • public: docs/tasks/README.md (board), docs/roadmap.md, docs/product/features/README.md
2. Pick the most useful next step, in this priority order:
   1. A task in review → remind the owner to review/commit it.
   2. A task in in-progress → offer to continue it (/start-task <id>).
   3. Open questions that block the current phase → ask them (AskUserQuestion: options + recommendation).
   4. The current phase's deliverables are all drafted but not yet reviewed → offer /tech-review <phase scope> before the owner approves the phase.
   5. The current phase's next deliverable (e.g. the next unwritten feature spec, research item, ADR).
   6. Untriaged inbox items → offer to triage them into the backlog or feature specs.
   7. A todo task whose dependencies are done → offer /start-task <id>.
3. Report briefly: where things stand (2–3 lines), the proposed next step, and 1–2 alternatives.
4. Ask before acting. On confirmation, do the step, using the matching skill (/new-task, /tech-review, /adr, …) where one exists. /start-task can only be run by the owner: tell the owner to type /start-task <id>.