Menu Bar Mismatch on Sub-Pages

## Issue Description:

Currently, the homepage uses a globally defined menu bar, which is intended only for the homepage. However, each Codeheat contest page (by year) has its own dedicated menu bar, linked specifically to sections on that page.

### Problem:

When a sub-page (e.g., a detail page or sub-route under a yearly Codeheat page) is created, the global homepage menu bar appears instead of the year-specific menu bar. This causes inconsistency in navigation and user experience.

_Homepage_

_Codeheat 2016_

### TASK:

- [x] [Add functions](https://github.com/fossasia/codeheat.org/issues/363#issuecomment-3151909332) to the functions.php file
- [x] [Demo](https://github.com/fossasia/codeheat.org/issues/363#issuecomment-3151995951) through a screencast