refactor(slay-the-spire-like): update combat targeting and effect logic

Refactor combat targeting types and effect application logic in the
Slay the Spire-like sample.

- Update `getEffectTargets` to use `IntentEffectTarget` and more
  descriptive target keys (e.g., `eachEnemy`, `randomEnemy`).
- Update `promptMainAction` to use `enemy` instead of `single` for
  card target types.
- Refactor `addInstantEffectTriggers` to remove unused effect loading
  and improve enemy/card instantiation logic

tests/samples/slay-the-spire-like/deck/factory.test.ts

@@ -33,7 +33,7 @@ function createTestCardData(id: string, name: string, desc: string): CardData {
     type: "item",
     costType: "energy",
     costCount: 1,
-    targetType: "single",
+    targetType: "enemy",
     effects: [],
   };
 }