Queries: Moved out or removed some class-level items

Also ran auto-removal of unused imports across app folder.

app/Entities/Models/Chapter.php

@@ -69,13 +69,4 @@ class Chapter extends BookChild
         ->orderBy('priority', 'asc')
         ->get();
     }
-
-    /**
-     * Get a visible chapter by its book and page slugs.
-     * @throws \Illuminate\Database\Eloquent\ModelNotFoundException
-     */
-    public static function getBySlugs(string $bookSlug, string $chapterSlug): self
-    {
-        return static::visible()->whereSlugs($bookSlug, $chapterSlug)->firstOrFail();
-    }
 }