[P1] Remove @ts-nocheck from tests and restore type-safe test coverage

[nkanf-dev]

Summary

Eliminate @ts-nocheck from the test suite and restore meaningful type checking for test code.

Why

Type-disabled tests allow interface drift to go unnoticed, which is already happening across store and service contracts.

Current evidence

• Multiple files under src/tests/ start with @ts-nocheck.
• Current tests reference APIs and selectors that no longer exist.

Scope

• Remove @ts-nocheck from test files incrementally.
• Fix the resulting type errors by aligning tests with real interfaces.
• Keep mocks and helper utilities typed.
• Add lint/type checking expectations for test code if practical.

Acceptance criteria

• Core unit, UI, and E2E test files no longer rely on @ts-nocheck.
• Test code compiles against current types.
• Interface drift is caught earlier by the toolchain.

Out of scope

• Full repository-wide strict-mode expansion beyond test-related changes.