feat: add Jitsi Meet template

[rohitmulani63-ops]

/claim #152
Closes #916

What is this PR about?

I added a Jitsi Meet template for Dokploy. The template includes the web, prosody, jicofo, and JVB services with the required domain, secret, and volume wiring for a self-hosted Jitsi deployment.

Checklist

• I read the template requirements in the repository README.
• I added the template files and metadata.
• I ran the template validation checks below.
• I tested the template in a running Dokploy instance.

Validation

• node dedupe-and-sort-meta.js
• npm --prefix build-scripts run validate-template -- --dir ../blueprints/jitsi
• npm --prefix build-scripts run validate-docker-compose -- --file ../blueprints/jitsi/docker-compose.yml
• git diff --check

Not run: full Docker runtime smoke test, because Docker is unavailable locally.

[rohitmulani63-ops]

Hi, just checking if the Jitsi Meet template needs any tweak. Happy to adjust the env notes or service config if needed.