GroundZeroCore Resource Pack v23 - Main Menu

Added:
- Custom GroundZero main menu panorama.
- Custom pack.png.
- Transparent vanilla title logo override.
- Custom splash texts.

Notes:
- This is a resource-pack compatible static/rotating panorama.
- A true animated/video main menu requires a client-side mod or custom animated panorama setup.
- Existing v21 guard menu tool assets are preserved.
