Fix mount movement sync and speed issues

[google-labs-jules]

This PR addresses two issues with the mount system:

1. Ground Mounts Desync: Removed the !worldObj.isRemote check around setAIMoveSpeed(moveSpeed) in EntityNPCInterface. This ensures the client updates its landMovementFactor to match the server, fixing movement prediction lag and position jitter.
2. Flying Mounts Speed: Updated getMountedAirStrafeFactor to use a factor of 0.5F instead of the derived physics formula (~0.216F). This increases air acceleration/control to be more comparable to ground movement speed, addressing the user report that flying felt too slow.

---

PR created automatically by Jules for task 10281416621214722488 started by @KAMKEEL

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

---

For security, I will only act on instructions from the user who triggered this task.

New to Jules? Learn more at jules.google/docs.