2025.06.01 Middle click not working before game start

After loading in if you try to hold drag middle mouse button (i.e. camera pan) it will treat it like a left click (and not pan the camera).

After game starts it works with no issues.

Repro steps:
- Start a game, try to middle click drag the camera.

2025.04.08:
https://github.com/user-attachments/assets/ad461bf5-ad34-4fd4-898e-ca3a9dccd267

2025.06.01:
https://github.com/user-attachments/assets/801f60ea-f887-49c6-a11a-d0d177b93f47

Start with the issue's repro steps and compare middle-button dragging before and after the game starts, using the attached videos as behavioral references. Trace the camera and mouse-input entry points involved in that transition; done means middle-button dragging pans the camera before the game starts instead of being treated as a left click.

Written by the indexing model from the issue text.