Feat: entity lock, entity spawn handling

[Oggymot]

Description: This PR introduces quality-of-life improvements focused on building precision and preventing accidental edits to placed props. For instance, when an editor is furnishing a house or an interior, it was previously common to accidentally select the building shell itself, leading to unintended movement or even deletion of the entire structure.

Key Changes:

• Entity Locking:

  • Added Lock/Unlock buttons to the entity Properties Menu.
  • Movement Protection: Locked entities cannot be moved or rotated using the mouse (gizmo) or keyboard controls.
  • Deletion Protection: Locked entities cannot be deleted individually via the standard delete keybind.
  • Focus Protection: Locked entities are ignored when trying to Focus (Alt) on an object, preventing accidental camera snapping to background props.
  • Note: The "Delete All" function in the Database Menu will still remove locked entities to allow for a complete cleanup.

• Spawn at Last Z-Coordinate:

  • Added a modifier key for spawning. Holding CTRL (mapped to INPUT_DUCK) while spawning an entity will place it at the exact Z-coordinate (height) of the previously spawned entity.
  • This allows for easier placement of multiple objects on tables, shelves, or floating platforms without them snapping to the ground.

• UI Updates:

  • Updated index.html and script.js to include the new Lock/Unlock controls in the properties interface.