Adds a loop test that asserts canTransition(status, 'GRILLING') for all
statuses in GRILL_TRIGGERABLE_FROM that support the transition, explicitly
documenting PLANNED as a valid re-grill entry point.
- GRILL_TRIGGERABLE_FROM now includes 'PLANNED' in actions/ideas.ts
- ALLOWED_TRANSITIONS PLANNED entry extended with 'GRILLING' in lib/idea-status.ts
- Updated canTransition test to reflect the new re-grill-from-PLANNED behavior