Coolify Setup Guide

[4w3Official]

Approved suggestion
Closes: #1697

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PR Summary

Low Risk
Low risk documentation-only change; the only functional impact is adding a new doc entry to navigation.

Overview
Adds a new Linux documentation page docs/server-linux-coolify.md describing how to install and secure a self-hosted Coolify instance (prereqs, install command with env vars, access, DNS/SSL setup, and first deployment).

Updates sidebars.js to include server-linux-coolify in the Linux software/services sidebar so the new guide appears in site navigation.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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