openspec-new-change

Start a new change using the experimental artifact-driven approach. **Store selection:** If the user names a store (a store is a standalone OpenSpec repo registered on this machine) or the work lives in one, run `openspec store list --json` to discover registered store ids, then pass `--store <id>` on the commands that read or write specs and changes (`new change`, `status`, `instructions`, `list`, `show`, `validate`, `archive`, `doctor`, `context`, `view`). Other commands do not take the flag. Hints printed by commands already carry the flag; keep it on follow-ups. Without a store, commands act on the nearest local `openspec/` root. **Input**: The user's request should include a change name (kebab-case) OR a description of what they want to build. **Steps** 1. **If no clear input provided, ask what they want to build** Ask the user (open-ended, no preset options): > "What change do you want to work on? Describe what you want to build or fix." From their description, derive a kebab-case name (e.g., "add user authentication" → `add-user-auth`). **IMPORTANT**: Do NOT proceed without understanding what the user wants to build. 2. **Determine the workflow schema** Use the default schema (omit `--schema`) unless the user explicitly requests a different workflow. **Use a different schema only if the user mentions:** - A specific schema name → use `--schema <name>` - "show workflows" or "what workflows" → run `openspec schemas --json` and let them c...