Re-Adds the radio noise volume slider (#96602)

## About The Pull Request
As the title said, re-adds the radio noise volume slider in the
preferences menu.


<details>
<summary>Images</summary>

Before:
<img width="920" height="770" alt="image"
src="https://github.com/user-attachments/assets/d182f6ed-7968-4fa7-a4df-73d1125e9c32"
/>

After:
<img width="920" height="770" alt="image"
src="https://github.com/user-attachments/assets/3e414130-ca04-4f76-8dbb-608bca1b84f4"
/>

</details>


## Why It's Good For The Game

People should be able to adjust the volume of radio beeps, since it can
be overwhelmingly loud when radio is really going off.

## Changelog
🆑
fix: Fixed the radio volume slider being missing in game preferences
/🆑

---------

Co-authored-by: Ghom <42542238+Ghommie@users.noreply.github.com>

code/modules/client/preferences/sounds.dm

@@ -150,6 +150,7 @@
 
 /// Controls radio noise volume
 /datum/preference/numeric/volume/sound_radio_noise
+	category = PREFERENCE_CATEGORY_GAME_PREFERENCES
 	savefile_key = "sound_radio_noise"
 	savefile_identifier = PREFERENCE_PLAYER