Fix Mattermost, Obsidian template

Fixed

• Fixed Mattermost template failing to start — the Site URL field was left empty by default, causing Mattermost to crash. It now auto-fills with your server address

• Fixed Obsidian template deployment failing with "invalid hostPort" — template variables like PORT were not being replaced in the final compose file

• Fixed Obsidian requiring HTTPS — updated the template to work with the newer Selkies-GStreamer streaming backend, now requires a domain with Traefik for automatic HTTPS

• Fixed "Add Domain" being blocked when nginx is detected — you can now install Traefik and add domains regardless of existing nginx on the VPS