Refactor architecture: improve env loading and command workflow

.env.example

@@ -4,6 +4,8 @@ DB_NAME=kyoko
 DB_PORT=5432
 DB_HOST=db
 DISCORD_BOT_TOKEN=your-discord-bot-token
+DISCORD_CLIENT_ID=your-discord-client-id
+DISCORD_GUILD_ID=your-discord-guild-id
 DB_DATA_DIR=./db-data
 DB_LOG_DIR=./db-logs
-DATABASE_URL=postgres://kyoko:kyoko@db:5432/kyoko
+DATABASE_URL=postgres://kyoko:kyoko@db:5432/kyoko