Fix schema for word root (#279)

* Add root_id into Words & rake task to Migrate WordRoots to words.root_id

* Minor code fix

Author: MuhammadAbdullaah

db/migrate/20250506055426_add_root_id_to_words.rb

@@ -0,0 +1,7 @@
+class AddRootIdToWords < ActiveRecord::Migration[7.0]
+  def change
+    c = Word.connection
+    c.add_column :words, :root_id, :integer
+    c.add_index :words, :root_id
+  end
+end

lib/tasks/migrate_word_roots.rake

@@ -0,0 +1,25 @@
+namespace :db do
+  desc "Migrate WordRoots to words.root_id"
+  task migrate_roots: :environment do
+    updated_count = 0
+    root_skipped = []
+
+    WordRoot.eager_load(:word).find_each do |word_root|
+      word = word_root.word
+      root = Root.find_by(id: word_root.root_id)
+
+      if word.nil? || word.root_id.present?
+        root_skipped << word_root.id
+        next
+      end
+
+      if root
+        word.update_column(:root_id, root.id)
+        updated_count += 1
+      end
+    end
+
+    puts "Data migration complete! #{updated_count} words updated with root_id."
+    puts "Skipped WordRoot IDs: #{root_skipped.join(', ')}"
+  end
+end