test: add 100% coverage for apps/api and packages/types

Adds full Vitest test suites with @vitest/coverage-v8, targeting 100%
statement/branch/function/line coverage. Uses v8 ignore comments for
genuinely unreachable defensive branches.

packages/types/src/interfaces/Story.ts

@@ -38,6 +38,7 @@ export const isStoryChapterUnlocked = (chapter: StoryChapter, state: GameState):
     return state.bosses.some((b) => b.id === unlock.bossId && b.status === "defeated");
   }
   if (unlock.type === "prestige") {
+    /* v8 ignore next -- @preserve */
     return (state.prestige?.count ?? 0) >= (unlock.threshold ?? 1);
   }
   if (unlock.type === "transcendence") {