The dashboard's stack dropdown hardcoded its options (python-cli/fastapi/
react-vite), so a supabase program showed "(none)" — the value had no matching
option. Make the backend the single source of truth instead:
- core: available_stacks() returns sorted(HANDLERS) — the stacks castle has
handlers for.
- castle-api: GET /stacks exposes it.
- cli: --stack choices derive from available_stacks() (drops the duplicated list).
- app: ProgramFields fetches /stacks (useStacks) and renders options from it,
always including the current value so it never silently blanks; StackBadge
gets a Supabase label.
A new backend stack now appears everywhere without a frontend edit.
Paul Payne
14145c9f15