fix: update Dockerfile to use Node.js 20 Alpine and correct commit SHA in .env.local; enhance nightly and release workflows with Docker Hub description and caching improvements

Dockerfile

@@ -1,5 +1,5 @@
-# Use Node.js 22 Alpine for smaller image size
-FROM node:22-alpine
+# Use Node.js 20 Alpine for smaller image size
+FROM node:20-alpine
 
 # Install pnpm globally
 RUN npm install -g pnpm@10.12.4