fix: show TGEAPCET OU region disclaimer on home page before submission

[A-Chronicle]

Description

When a student selects TGEAPCET with OU region on the home page, no warning appears about limited OU-specific data. The disclaimer only shows after submission on the results page. This fix mirrors the existing EWS category disclaimer logic to also show when OU region is selected.

Before: Disclaimer only showed for EWS category
After: Disclaimer shows for both EWS category and OU region selection

Fixes #298

Checklist

• Small, focused correctness fix with clear before/after behavior
• Zero breaking changes
• Follows existing code patterns (same disclaimer component, same styling)

[suryabulusu]

Review note for Amogh / maintainers:

This PR is trying to solve the same real issue as #299: TGEAPCET OU-region students should see the data limitation warning before submitting the form.

Recommendation: do not merge both #299 and #300. Pick one implementation, or make a fresh minimal PR. This PR also includes unrelated formatting/no-op changes outside the actual product fix, so it is not clean as-is.

Product decision is straightforward: the home page should show the OU warning just like the results page already does. Engineering cleanup needed: keep the diff limited to the relevant disclaimer logic in pages/index.js.