PM-5584: Hide time left for inactive assignments

[jmgasper]

What was broken
Completed, offer rejected, and terminated assignment rows in the Flexi-Talent engagement detail panel still showed Time Left and overdue metadata even though those assignments were no longer active.

Root cause
The engagement detail assignment renderer always displayed the time-left field whenever backend timing data existed and did not check the assignment status before treating the row as current work.

What was changed
Added a current-assignment status check for selected and assigned rows, and render the Time Left metadata only for those active statuses.

Any added/updated tests
Added an EngagementsView test covering completed, offer rejected, and terminated rows with overdue timing data to ensure their Time Left/overdue metadata is hidden.

Validation:

• yarn test:no-watch EngagementsView --runInBand passed.
• yarn lint passed.
• yarn run build passed with existing warnings.
• yarn test:no-watch --runInBand was run, but existing unrelated suites failed outside this ticket area.