fix(dashboard): prevent stale evolution proposals after employee switch

[yuzhiyang1]

Summary

• keep evolution proposals scoped to the currently selected employee before rendering
• invalidate superseded loads so an older employee response cannot overwrite the current employee data
• add regression coverage for both the loading-window leak and out-of-order response race
• fix the dashboard test mock so the evolution endpoint returns the correct response shape

Reproduction

1. Open employee A and wait for its evolution proposals to load.
2. Switch to employee B while B's proposal request is still pending.
3. Employee A's proposals remain visible and actionable during the load.
4. With overlapping requests, a late response for employee A can overwrite employee B's already loaded proposals.

Because proposal actions are issued by proposal ID, stale rows could lead an administrator to act on the previous employee's proposal from the current employee view.

Validation

• npm test — 46 test files, 202 tests passed
• npm run build
• npm run i18n:check
• npm run config:check