Replace Tailwind CSS CDN with Vite build

[andriytyurnikov]

Summary

Replaces the @tailwindcss/browser CDN runtime with build-time CSS compilation using Vite and @tailwindcss/vite.

Supersedes #282 (which used custom shadow-cljs build hooks and was reverted in e080856).

Why

The browser runtime generates CSS at page load:

• FOUC on every page load
• ~100KB runtime JS downloaded and executed per visit
• CDN dependency — no offline dev, outage = broken UI
• No custom CSS — can't use @layer, @apply, or plugins

Approach: Vite instead of shadow-cljs hooks

The previous attempt (#282) used a custom Clojure namespace (tailwind_hook.clj) to shell out to the Tailwind CLI from shadow-cljs build hooks. This required managing child processes, shutdown hooks, and had race conditions on one-shot builds.

This PR uses Vite — an industry-standard build tool with first-class Tailwind support. No custom process management code. The CSS build is a standard npx vite build command, completely independent of shadow-cljs.

	#282 (shadow-cljs hooks)	This PR (Vite)
Custom Clojure code	97-line tailwind_hook.clj	None
Process management	Manual (ProcessBuilder, shutdown hooks)	Vite handles it
Dev watch	Custom watch process lifecycle	npx vite build --watch
Build tool	npx @tailwindcss/cli via Clojure shelling	npx vite build
Manifest format	Custom EDN	Standard Vite JSON

What changed

File	Change
vite.config.js	Vite config with @tailwindcss/vite plugin, outputs hashed CSS + JSON manifest to resource/public/
src/cljs/.../ui/css/main.css	Tailwind v4 entry: @import "tailwindcss" + @source directive
resource/index.html	CDN script replaced by {{MAIN_CSS}} placeholder
server.clj	css-tag reads Vite JSON manifest for hashed filename; falls back to CDN when no compiled CSS exists
scripts/build-ui.sh	Added npx vite build before shadow-cljs release
package.json	Added vite and @tailwindcss/vite dev dependencies
.gitignore	Vite CSS output + manifest
shadow-cljs.edn	Unchanged — no build hooks needed

CDN fallback for REPL workflow

The server checks for compiled CSS at request time. If found, serves <link> to the hashed file. If not (e.g., REPL started without a prior build), falls back to the original CDN <script> tag. The REPL workflow ((aor/start-ui ipc)) continues to work with zero setup.

Developer workflows

# Dev — two terminals
npx vite build --watch    # CSS (rebuilds on change)
npx shadow-cljs watch :dev  # JS

# Production
scripts/build-ui.sh         # runs both vite build + shadow-cljs release

# REPL only (no build needed)
# lein repl → (aor/start-ui ipc)
# CSS falls back to CDN automatically

Test plan

• npx vite build — produces main.HASH.css (39KB) + css-manifest.json in 1.9s
• npx shadow-cljs compile :dev — unaffected, builds normally
• scripts/build-ui.sh — produces both hashed CSS and JS
• Server serves built CSS when available
• Server falls back to CDN when no compiled CSS exists