Remove N+1 from grid object models

Reimplementing `character` `summon` and `weapon` was making N+1s which made queries really slow

app/models/grid_character.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class GridCharacter < ApplicationRecord
-  has_one :object, class_name: 'Character', foreign_key: :id, primary_key: :character_id
+  belongs_to :character, foreign_key: :character_id, primary_key: :id
 
   belongs_to :awakening, optional: true
   belongs_to :party,
@@ -78,10 +78,6 @@ class GridCharacter < ApplicationRecord
                 'aetherial_mastery')
   end
 
-  def character
-    Character.find(character_id)
-  end
-
   def blueprint
     GridCharacterBlueprint
   end

app/models/grid_summon.rb

@@ -1,19 +1,16 @@
 # frozen_string_literal: true
 
 class GridSummon < ApplicationRecord
+  belongs_to :summon, foreign_key: :summon_id, primary_key: :id
+
   belongs_to :party,
              counter_cache: :summons_count,
              inverse_of: :summons
   validates_presence_of :party
-  has_one :object, class_name: 'Summon', foreign_key: :id, primary_key: :summon_id
 
   validate :compatible_with_position, on: :create
   validate :no_conflicts, on: :create
 
-  def summon
-    Summon.find(summon_id)
-  end
-
   def blueprint
     GridSummonBlueprint
   end

app/models/grid_weapon.rb

@@ -1,13 +1,13 @@
 # frozen_string_literal: true
 
 class GridWeapon < ApplicationRecord
+  belongs_to :weapon, foreign_key: :weapon_id, primary_key: :id
+
   belongs_to :party,
              counter_cache: :weapons_count,
              inverse_of: :weapons
   validates_presence_of :party
 
-  has_one :object, class_name: 'Weapon', foreign_key: :id, primary_key: :weapon_id
-
   belongs_to :weapon_key1, class_name: 'WeaponKey', foreign_key: :weapon_key1_id, optional: true
   belongs_to :weapon_key2, class_name: 'WeaponKey', foreign_key: :weapon_key2_id, optional: true
   belongs_to :weapon_key3, class_name: 'WeaponKey', foreign_key: :weapon_key3_id, optional: true
@@ -33,10 +33,6 @@ class GridWeapon < ApplicationRecord
     GridWeaponBlueprint
   end
 
-  def weapon
-    Weapon.find(weapon_id)
-  end
-
   def weapon_keys
     [weapon_key1, weapon_key2, weapon_key3].compact
   end