add rake tasks for character season/series CSV export and import

lib/tasks/characters.rake

@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+require 'csv'
+
+namespace :characters do
+  desc 'Export characters to CSV for season/series mapping'
+  task export_for_mapping: :environment do
+    output_path = ENV['OUTPUT'] || Rails.root.join('export', 'characters_for_mapping.csv')
+    FileUtils.mkdir_p(File.dirname(output_path))
+
+    headers = %w[id granblue_id name_en name_jp rarity element season series gacha_available]
+
+    CSV.open(output_path, 'w', headers: headers, write_headers: true) do |csv|
+      Character.order(:id).find_each do |character|
+        csv << [
+          character.id,
+          character.granblue_id,
+          character.name_en,
+          character.name_jp,
+          character.rarity,
+          character.element,
+          character.season,
+          character.series&.join(','),
+          character.gacha_available
+        ]
+      end
+    end
+
+    count = Character.count
+    puts "Exported #{count} characters to #{output_path}"
+  end
+
+  desc 'Import season/series data from curated CSV'
+  task :import_season_series, [:csv_path] => :environment do |_t, args|
+    csv_path = args[:csv_path]
+    unless csv_path && File.exist?(csv_path)
+      puts "Usage: bundle exec rake characters:import_season_series[path/to/curated.csv]"
+      puts "Error: CSV file not found at #{csv_path}"
+      exit 1
+    end
+
+    test_mode = ENV['TEST'] == 'true'
+    updated = 0
+    skipped = 0
+    errors = []
+
+    CSV.foreach(csv_path, headers: true) do |row|
+      character = Character.find_by(id: row['id'])
+      unless character
+        errors << "Character not found with id: #{row['id']}"
+        next
+      end
+
+      # Parse season (can be nil or integer)
+      season = row['season'].presence&.to_i
+
+      # Parse series (comma-separated integers or empty)
+      series = row['series'].presence&.split(',')&.map(&:to_i) || []
+
+      # Parse gacha_available (boolean)
+      gacha_available = row['gacha_available']&.downcase
+      gacha_available = case gacha_available
+                        when 'true', '1', 't' then true
+                        when 'false', '0', 'f' then false
+                        else true # default
+                        end
+
+      if test_mode
+        puts "Would update #{character.name_en}: season=#{season}, series=#{series}, gacha_available=#{gacha_available}"
+        updated += 1
+      else
+        if character.update(season: season, series: series, gacha_available: gacha_available)
+          updated += 1
+        else
+          errors << "Failed to update #{character.name_en} (#{character.id}): #{character.errors.full_messages.join(', ')}"
+        end
+      end
+    end
+
+    puts "Updated: #{updated}, Skipped: #{skipped}, Errors: #{errors.count}"
+    errors.each { |e| puts "  - #{e}" } if errors.any?
+    puts "(TEST MODE - no changes made)" if test_mode
+  end
+end