Introduces the plumbing layer for Phase 3: GameStateResource wraps
solitaire_core::GameState, DragState tracks in-progress drags, and
SyncStatusResource holds runtime sync status. GamePlugin routes
Draw/Move/Undo/NewGame request events into GameState and emits
StateChangedEvent and GameWonEvent for downstream systems.
Also adds the Phase 3 implementation plan under docs/superpowers/plans/.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
funman300
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