Add database schema and migration tasks

Rakefile

@@ -0,0 +1,25 @@
+require "dotenv/load" if ENV.fetch("RACK_ENV", "development") == "development"
+
+require_relative "lib/database"
+
+Sequel.extension :migration
+
+MIGRATIONS_PATH = File.expand_path("db/migrations", __dir__)
+
+namespace :db do
+  desc "Apply pending database migrations"
+  task :migrate do
+    Sequel::Migrator.run(DB, MIGRATIONS_PATH)
+  end
+
+  desc "Display current migration version"
+  task :version do
+    version = if DB.tables.include?(:schema_info)
+      DB[:schema_info].get(:version) || 0
+    else
+      0
+    end
+
+    puts "Schema version: #{version}"
+  end
+end