Switch to Node.js 16 LTS, upgrade TypeScript, ESLint, and other dependencies (#395)

* Upgrade TypeScript, ESLint, and other dependencies

This also cleans up various other files where newer ESLint rules complained

* Set CI and CD to use Node.js version 16

* Small tweak

* Fix CD version printing

* Add nvm version for Cloudflare Pages

.deployment/cd.sh

@@ -3,8 +3,14 @@
 echo 🔧 Install Rust
 curl https://sh.rustup.rs -sSf | sh -s -- -y
 export PATH=$PATH:/opt/buildhome/.cargo/bin
+echo rustc version:
+rustc --version
 
 echo 🚧 Install Node dependencies
+echo node version:
+node --version
+echo npm version:
+npm --version
 cd frontend
 npm install