Global Target Resource Setting for Dispatch Tower

Currently, setting a priority resource (Target Resource) is only possible per excavator, making it tedious to manage multiple units in one tower's area.
Add a "Target Resource" dropdown to the Dispatch Tower interface. When set, this command applies to all assigned excavators, making mass resource switching (e.g., from limestone to iron) instant.
Benefits:
1. Saves significant management time.
2. Improves logistics flexibility.
3. Intuitive control from the central tower.
4. Better strategic control over mining operations.