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>

.gitignore

@@ -32,7 +32,7 @@ go.work.sum
 .LSOverride
 
 # Icon must end with two \r
-Icon
+Icon
 
 # Thumbnails
 ._*
@@ -56,6 +56,9 @@ Temporary Items
 # Project artifacts
 releases/
 
+# Node (Tailwind CSS build tooling — node_modules not committed, tailwind.min.css is)
+node_modules/
+
 # Local runtime secrets
 config.yaml
 data/settings.db