Fix migrations that can no longer be applied

The migrations could no longer be applied on an empty database, mainly
because they referred to models that no longer existed. Replaced the
model references with direct table access that will always be correct at
the time the migration is applied.

Also removed conflicting indexes in table renames.

db/migrate/20240813200622_rename_organizations_to_accounts.rb

@@ -1,9 +1,6 @@
 class RenameOrganizationsToAccounts < ActiveRecord::Migration[8.0]
   def change
     rename_table :organizations, :accounts
-    add_index :accounts, :name, unique: true
-
     rename_column :users, :organization_id, :account_id
-    add_index :users, :account_id
   end
 end

db/migrate/20240916191616_create_projects.rb

@@ -7,7 +7,5 @@ class CreateProjects < ActiveRecord::Migration[8.0]
 
       t.timestamps
     end
-
-    Account.first.projects.create! name: "Writebook", creator: User.first
   end
 end

db/migrate/20240916193936_add_project_to_bubbles.rb

@@ -4,7 +4,8 @@ class AddProjectToBubbles < ActiveRecord::Migration[8.0]
       t.references :project, null: true
     end
 
-    Bubble.update_all project_id: Project.first.id
+    execute "update bubbles set project_id = (select id from projects limit 1)"
+
     change_column_null :bubbles, :project_id, false
   end
 end

db/migrate/20241001200953_add_account_to_tags.rb

@@ -4,7 +4,8 @@ class AddAccountToTags < ActiveRecord::Migration[8.0]
       t.references :account, null: true
     end
 
-    Tag.update_all account_id: Account.first.id
+    execute "update tags set account_id = (select id from accounts limit 1)"
+
     change_column_null :tags, :account_id, false
   end
 end