Setting Up Cloudwatch Alarm Notifications

This sets up the notification plumbing for CloudWatch alarms using SNS topics and subscriptions. You'll use it when you need alerts to actually reach people via email, SMS, or webhooks instead of just firing silently into the void. It handles the encrypted topic creation, configures the IAM policies so CloudWatch can publish to SNS, and walks through linking everything together. The troubleshooting section covers the usual gotchas like unconfirmed email subscriptions and phone numbers not being in E.164 format. Solid for getting the alerting infrastructure right the first time instead of debugging why notifications aren't showing up during an actual incident.