Refine exams view form typing

[Saby-Bishops]

Summary

• replace the untyped exam answer control with a typed FormControl reflecting exam answer shapes
• add helper type guards to keep validation and answer restoration aligned with typed options
• update answer handling to work with the typed controls across selection workflows

Testing

• npm run lint (fails: ng: not found in environment)

---

Codex Task

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.