remove demo game

state.save.go

@@ -0,0 +1,6 @@
+package pncdsl
+
+// Save/Load are stubbed out in this milestone — the runtime state machine
+// is in place, but JSON serialization will land alongside the polish pass.
+func (g *Game) Save(slot int) error { _ = slot; return nil }
+func (g *Game) Load(slot int) error { _ = slot; return nil }