fix: PkmFileEntity key conflict errors

[Chnapy]

Fix error throwing from this reproduce steps:

Given these actions:

• Move: (pkm) main -> save
• Move attached: (same pkm) save -> main
• Evolve: (same pkm) save
• Remove action: Evolve

Triggers this kind of error:

System.InvalidOperationException:
The instance of entity type 'PkmFileEntity' cannot be tracked because another instance with the key value '{Filepath: ./tmp/storage/foobar.xk3}' is already being tracked.
When attaching existing entities, ensure that only one entity instance with a given key value is attached.