Re-enable type checking and tighten test typings

[anthuanvasquez]

Context

Project messaging says type-safe, but Nuxt config currently has typescript.typeCheck = false. Several tests rely on broad @ts-expect-error usage.

Problem

Type regressions can pass unnoticed and reduce maintainability.

Proposed Solution

• Re-enable typeCheck in nuxt.config.ts (or introduce phased gate if immediate enablement fails).
• Reduce unnecessary @ts-expect-error in tests by improving typings/mocks.
• Add explicit typecheck command to CI if required.

Acceptance Criteria

• Type check strategy documented and active
• Reduced unnecessary @ts-expect-error
• No type-related regressions in pipeline

Notes

If full activation is too disruptive, ship phased targets with deadlines.