RoxyandGitHub c013c6f4f2 Fix the featherweight quirk not doing anything (#3669) ...

## About The Pull Request

Turns out that's what that file did
- Moved the featherweight stuff into the main `riding_mob.dm` because
we've already torn that file up by necessity
- Update the logic to work with upstream riding offset changes
- Fix layers being wrong on fireman carrying/piggybacks

## Why It's Good For The Game

Fixes #3662 

## Proof Of Testing
<details>
<summary>Screenshots/Videos</summary>


![image](https://github.com/user-attachments/assets/b8231d28-5776-4573-aa0b-b9dc6c875659)

</details>

## Changelog
🆑
fix: fixed the featherweight quirk doing nothing when you're picked up
fix: fixed rider always layering above carrier when fireman
carrying/piggybacking
/🆑

2025-04-29 16:05:03 -07:00

..

riding_minigame.dm

The big fix for pixel_x and pixel_y use cases. (#90124)

2025-03-28 14:18:45 +00:00

riding_mob.dm

Fix the featherweight quirk not doing anything (#3669)

2025-04-29 16:05:03 -07:00

riding_vehicle.dm

Fixes rideable mob layering (#89919)

2025-03-12 17:22:14 -04:00

riding.dm

Pixel adjustments to mobs are now sourced / Refactors riding (#89320)

2025-03-12 16:00:01 -04:00