chore: reduce memory usage

[Chnapy]

• use MemoryCache (20s) for each StaticData entities and SavePkms DTOs
• split StaticData in multiple cached entities: Evolves (lot of usages), Species (heavy), Spritesheets, Others
• remove save clonage since each one can be heavy (>5Mo), so backup save-part is now file-based
• merge save-related services, simplify logic

Backend memory is now expected to be around 200-300Mo in idle mode depending of opened saves.