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

src/state/__tests__/viewModel.test.ts

@@ -7,7 +7,7 @@ function testContent() {
   return buildContent({
     resources: [{ id: 'gold', name: 'Gold', startAmount: 4 }],
     actions: [
-      { id: 'forage', name: 'Forage', durationMs: 200, yields: { resourceId: 'gold', amount: 1 } },
+      { id: 'forage', name: 'Forage', durationMs: 200, yields: [{ resourceId: 'gold', amount: 1 }] },
     ],
   });
 }