feat(content): add action costs and multi-yield schema

src/engine/game.ts

@@ -50,6 +50,8 @@ export function tickGame(state: GameState, content: Content, tickMs: number): vo
   state.actionElapsedMs += tickMs;
   while (state.actionElapsedMs >= action.durationMs) {
     state.actionElapsedMs -= action.durationMs;
-    state.resources[action.yields.resourceId] += action.yields.amount;
+    for (const y of action.yields) {
+      state.resources[y.resourceId] += y.amount;
+    }
   }
 }