Better PDF reports, enable virtual memory ♻

Major changes:

• Dedicate 2G of disk space to virtual memory into /swapfile
• Generate PDF reports with ccjmne/docker-puppeteer-html2pdf
• Drop wkhtmltopdf entirely

QoL improvements:

• Introduce "message of the day" with update instructions
• Update Postgres JDBC to newest version (42.2.5)