Improve performance on poor connections: local assets, gzip, caching

- Replace Tailwind CDN (~350KB) with purged local CSS (~22KB)
- Replace htmx unpkg CDN with local static file
- Add Gzip middleware (standard library, sync.Pool) for all responses
- Add Cache-Control: public, max-age=3600 for /static/* assets
- Reduce status polling interval from 5s to 30s
- Add scripts/build-css.sh for CSS regeneration after template changes
- Document in bible-local/operations.md and history.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

bible-local/operations.md

@@ -163,6 +163,42 @@ xattr -d com.apple.quarantine /path/to/pfs-darwin-arm64
 
 ---
 
+## Frontend Assets (Tailwind CSS)
+
+Static assets are embedded into the binary from `web/static/`. CSS and JS are served locally —
+no external CDN requests at runtime.
+
+### Regenerate Tailwind CSS
+
+Run this after adding new Tailwind utility classes to any HTML template:
+
+```bash
+scripts/build-css.sh
+# or directly:
+node_modules/.bin/tailwindcss -i tw-input.css -o web/static/tailwind.min.css --minify
+```
+
+First-time setup (requires Node.js):
+
+```bash
+npm install
+```
+
+`node_modules/` is excluded from git. `web/static/tailwind.min.css` **is** committed —
+rebuilding is only needed when templates change.
+
+### Files involved
+
+| File | Purpose |
+|------|---------|
+| `tailwind.config.js` | Content paths for class scanning |
+| `tw-input.css` | Tailwind input (base/components/utilities directives) |
+| `web/static/tailwind.min.css` | Generated output — committed, embedded into binary |
+| `web/static/js/htmx.min.js` | htmx — committed, embedded into binary |
+| `scripts/build-css.sh` | Shortcut to regenerate CSS |
+
+---
+
 ## Requirements
 
 - Go 1.22+