New endpoints:
- GET /api/state/buildable: buildings filtered by completed research (unlocked/locked)
- POST /api/action/toggle: toggle building on/off (save power, control workflow)
- POST /api/action/set_recipe: set building recipe (e.g. Rock Crusher mode)
- POST /api/action/empty: empty building storage (drop all contents)
- POST /api/action/cancel_errand: cancel all errands at a building
Improved research: proper prerequisite validation, tech queueing, research station check
CLI: buildable [filter], toggle, set_recipe, empty, cancel_errand
Updated SKILL.md with new endpoint docs