Just write code: improving developer experience for Cloudflare Workers

Introduced Wrangler, the official Workers CLI, for compiling Rust, C, and C++ to WebAssembly, creating single or multi-file JavaScript applications, installing NPM dependencies, adding KV namespaces and bindings, and publishing projects. Enhanced documentation with new tutorials for deploying Slack bots, QR code generators, and serving/caching files from cloud storage. Enabled multi-script deployment for breaking code into logical components. Launched workers.dev subdomains for deployment without a custom domain. Introduced a free tier allowing up to 100,000 requests per day. Improved the UI for a streamlined sign-up to deployment experience.