Add Linkding integration: new CT template (ct/linkding.sh) and installer (install/linkding-install.sh) to deploy Linkding as a container. Installer fetches the GitHub release, builds the frontend, compiles the SQLite ICU extension, creates .env with generated admin password, and installs systemd services (linkding, linkding-tasks). Also add frontend metadata (frontend/public/json/linkding.json) for the app catalog. Minor tweak: remove unused import_local_ip from install/wger-install.sh.
Replaces the custom settings directory with a .env file for configuration. Updates backup and restore logic to handle .env instead of settings, and sets required Django environment variables explicitly. Simplifies installation and update scripts for better maintainability and security.
Replaces 'uv sync --no-dev' and editable pip install with 'uv venv' and standard pip install in both wger.sh and wger-install.sh. This streamlines the installation and update process for wger.
