refactor(test): 收敛 bootstrap/useAuthStore 测试脚手架类型强转 #79

Source

From PR #65 review follow-up: #65 (comment)

Context

OUT_OF_SCOPE legacy item: bootstrap.spec has inline helper types and useAuthStore.spec uses mock double-casts. These are existing test scaffolding issues, not introduced by PR #65, so they were intentionally left out of that PR.

Desired direction

Refactor the test helpers so auth/bootstrap mocks are typed clearly and reusable where it reduces local casting noise. Avoid changing runtime store or bootstrap behavior.

Acceptance

• bootstrap.spec no longer needs ad-hoc inline types where a local helper type/factory is clearer.
• useAuthStore.spec avoids unnecessary double-casts around mocked @gocell/request.
• Auth store and bootstrap tests remain equivalent in behavior.