[BUGFIX] Prevent infinite redirect loop by validating URL hash formatting

[aryan-gupta7]

Description

This PR fixes the infinite redirect loop that occurs when a user attempts to switch the application language.

The core of the issue was located in lib/utils/router.ts within the customRoute function. Previously, the code updated the location.hash by unconditionally prepending a forward slash to the match.hashString. Since match.hashString often already contained a leading slash, this resulted in malformed URLs (e.g., //de/map). These malformed paths failed to satisfy the router's regex requirements, causing the application to fail to recognize the state and trigger another reload, thus starting the loop.

The Fix:
The logic now checks for the existence of a leading slash in match.hashString before constructing the final URL hash.

Motivation and Context

• Fixes: Issue #284
• Problem: Users were unable to change languages without being trapped in a series of infinite page reloads.

How Has This Been Tested?

• Manual Test: Verified that switching languages now correctly reloads the page once with a properly formatted URL (e.g., #/de/map) and correctly initialized translations.
• Build Test: Ran npm run build to confirm the changes compile correctly within the project structure.

Checklist:

• My code follows the code style of this project. (CI will test it anyway and also needs approval)
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

[maurerle]

when choosing en with en as default, another # is added:

Can you fix this as well?

[aryan-gupta7]

I just checked it, yeah this happens when you try to change language to the current language.
I think I can fix this.