Stop Leaking API Keys: Managing Secrets in Kamal 2

I see developers make a mistake that can ruin their entire month. They are building a new Rails SaaS. They get their Stripe secret key, their OpenAI key, and their AWS credentials. To deploy the app, they create a file called .env.production on their laptop, paste the keys inside, and deploy. Then, late on a Friday night, they accidentally type git add . and push that file to a public GitHub repository. Within exactly 4 seconds, automated bots scrape those keys. By Saturday morning, hackers have