pick-next-prompt

# Pick Next Prompt Pick the next ready shell from a prompt plan index at `.turbo/prompt-plans/<slug>.md` and hand it to `/turboplan` in shell mode. ## Step 1: Resolve the Prompt Plan Index Determine which prompt plan index to read using these rules in order: 1. **Explicit path** — If the user passed a file path, use it 2. **Explicit slug** — If a slug was passed, resolve to `.turbo/prompt-plans/<slug>.md` 3. **In-progress wins** — Glob `.turbo/prompt-plans/*.md`. If exactly one index has any prompt with `Status: in-progress`, use it. This is the prompt plan currently being worked on. 4. **Single file** — If exactly one index file exists, use it 5. **Most recent** — If no index has an in-progress prompt and rule 3 did not resolve, use the most recently modified file 6. **Legacy fallback** — If `.turbo/prompt-plans/` does not exist but `.turbo/prompts.md` exists, tell the user to re-run `/create-prompt-plan` to upgrade to shells, and halt. 7. **Nothing found** — If no prompt plan exists, tell the user to run `/turboplan` for a complex task (which will route to `/create-spec` + `/create-prompt-plan`) and stop If multiple files have in-progress prompts (concurrent work in different feature branches), use `AskUserQuestion` to let the user pick. State the resolved index path before continuing. Read the index file. Each prompt entry uses bold-prefixed inline markers under a `## Prompt N:` heading. Parse: - Prompt number and title (from the `## Prompt N: <title>` heading) - S...