Constellation Sync 0.4.8

• Plugin sync is removed: the enabled community plugins list and per-plugin settings no longer sync, and everything under the plugins folder is hard-excluded. Stale selections migrate out automatically; existing files on devices and on the branch are left untouched (frozen, not deleted).
• Config defaults are now platform-aware: mobile skips hotkeys by default since hardware-modifier shortcuts barely apply there. Each device keeps its own selection, so Mac, Windows and mobile can differ.