Add sqlite database

lib/database.rb

@@ -0,0 +1,15 @@
+require "fileutils"
+require "sequel"
+
+database_path = File.expand_path(
+  ENV.fetch("DATABASE_PATH", "../db/development.sqlite3"),
+  __dir__
+)
+
+FileUtils.mkdir_p(File.dirname(database_path))
+
+DB = Sequel.sqlite(
+  database_path,
+  timeout: 5_000,
+  connect_sqls: ["PRAGMA foreign_keys = ON"]
+)