Integration pages, comparisons and a migration guide

The EvoHub website got more useful for teams evaluating or setting up EvoHub.

• Integrations: a directory at evohub.io/integrations with a page for each supported tool and the same setup steps you see in the app.
• Migration guide: a step-by-step guide for moving an existing on-call setup to EvoHub.
• Comparisons: pages comparing EvoHub with other on-call, uptime, status page and retrospective tools, including pricing models and when another tool may fit better.
• Pages load faster and read properly before scripts run, which also helps search engines and AI assistants understand them.
• People who sign up with Google or GitHub now receive the welcome email too.