Externalize configuration values

Avoid hardcoding deployment-specific values—such as usernames, channel IDs, thresholds, or other identifiers—directly in source code. Instead, define them as environment variables or config entries (e.g., CLICKHOUSE_HQL_USER instead of a literal "hql_user", or ALERT_BANNER_ID_DELAY_IN_QUEUE/FIRE_ALERT_CHANNEL as env vars rather than inline constants). This is especially important for self-hosted or multi-environment deployments where these values must be customizable without code changes.

Additionally, when a feature depends on optional configuration (e.g., Slack webhook/channel settings), guard the code path so it skips gracefully if that configuration is not set, rather than attempting the action and failing. For example:

if (!env.SLACK_ALERT_CHANNEL) {
  return; // skip sending alert if not configured
}
await alertManager.sendSlackMessageToChannel(env.SLACK_ALERT_CHANNEL, ...);

This keeps configuration centralized, makes deployments portable, and prevents runtime failures when optional settings are absent.