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/history.md

@@ -5,6 +5,37 @@
 
 ---
 
+## 2026-03-14: Performance improvements for poor network connections
+
+### Decision
+
+Replaced external CDN dependencies with locally-served assets and added server-side compression
+to improve load times on poor or high-latency connections.
+
+### What changed
+
+- **Tailwind CSS**: replaced `cdn.tailwindcss.com` JIT runtime (~350KB) with a purged and minified
+  local CSS file `web/static/tailwind.min.css` (~22KB). Generated via `tailwindcss` CLI scanning
+  all templates. `package.json`, `tailwind.config.js`, `tw-input.css`, and `scripts/build-css.sh`
+  added for CSS regeneration. `node_modules/` excluded from git.
+- **htmx**: replaced unpkg CDN with locally-served `web/static/js/htmx.min.js` (~47KB).
+- **Gzip middleware**: added `internal/middleware/gzip.go` — compresses all responses using
+  standard library `compress/gzip`. Uses a sync.Pool to reuse writers. Registered first in the
+  middleware chain in `cmd/pfs/main.go`.
+- **Cache-Control**: added `internal/middleware/static_cache.go` — sets
+  `Cache-Control: public, max-age=3600` for all `/static/*` requests so browsers reuse
+  CSS/JS across navigations without re-downloading.
+- **Polling interval**: `base.html` status polling reduced from 5 s to 30 s to cut background
+  network traffic.
+
+### Consequences
+
+- When adding new Tailwind classes to templates, run `scripts/build-css.sh` to regenerate CSS.
+- First page load now requires no external network requests.
+- Binary size increases by ~70KB (embedded static assets).
+
+---
+
 ## 2026-03-07: Embedded Scheduler with MariaDB Advisory Locks
 
 ### Decision

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+