Align defaults to Debian 12 and remove the explicit Java setup call from the installer. Updated ct/jitsi-meet.sh to default var_version to 12, json/jitsi.json to reflect version "12", and removed the `JAVA_VERSION=17 setup_java` line from install/jitsi-meet-install.sh so Java is no longer forced by the installer.
Add container templates, install scripts and metadata for six applications: BirdNET-Go, ERPNext, Jitsi Meet, Storybook, Storyteller and Tube Archivist. New files include ct/* scripts (container templates and update handlers), install/* scripts (installation and systemd service setup, dependency installation and build steps) and json/* metadata entries (app catalog data, default resources, ports and notes). Each install script configures required dependencies, creates services, and prepares runtime configuration (e.g. DB, ElasticSearch, Node/Python environments, ffmpeg/Readium). This commit enables automated LXC provisioning and update flows for these apps.
