Replace the per-config unlock fields (unlock_at_station_level,
unlock_requires) with a first-class unlock-group concept defined in a
new unlocks.toml. An unlock group is now the unit of loot: awarding one
grants all its members (ships, modules, buildings, assembler recipes) at
once, so a building and a module can be unlocked together.
- Buildings become lockable (REQ-LOCK-BUILDING); locked types are hidden
from the build grid and skipped in blueprint placement.
- Items absent from every unlock group start unlocked (replaces -1).
- New unlocked_at_start flag on assembler recipes for graph-unreachable
base recipes (e.g. building blocks).
- Group display name derived from id for now; no display_name field yet.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc