- Refactored `set_from_slug` to use `includes` for eager loading associated models:
- `user`, `job`, `raid` (with `group`)
- `characters` (with `character` and `awakening`)
- `weapons` (with `weapon`, `awakenings`, `weapon_key1`, `weapon_key2`, `weapon_key3`)
- `summons` (with `summon`)
- `guidebooks` (`guidebook1`, `guidebook2`, `guidebook3`)
- `source_party`, `remixes`, `skills`, and `accessory`
- This change improves query efficiency by reducing N+1 queries and ensures all relevant associations are preloaded.
- Removed redundant favorite check as it was not necessary in this context.