Add Node 26 to CI matrix

[Ma11hewThomas]

Summary

• add Node 26 to the test/build matrix
• move quality and security jobs from Node 22 to Node 26
• keep the existing standard CI structure

Verification

• ruby -e "require 'yaml'; Dir['.github/workflows/*.{yml,yaml}'].each { |f| YAML.load_file(f); puts f }"
• source ~/.nvm/nvm.sh && nvm use 24.2.0 && npm run all
• source ~/.nvm/nvm.sh && nvm use 24.2.0 && npm audit --omit=dev