Add guestbook with WebAuthn admin and SQLite

Introduce server-rendered guestbook and moderation portal.
Persist data in SQLite (better-sqlite3); add WebAuthn YubiKey
admin auth, rate-limiting, spam heuristics, and sanitization.
Switch Docker image to run Node/standalone Astro (remove nginx),
update docker-compose, Dockerfile, astro.config, and package.json.
Add .env.example, docs/guestbook.md, gitignore updates, layouts,
API routes, and supporting lib/components/pages for the feature.

CLAUDE.md

@@ -6,7 +6,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 **Project:** Cozy Den - Personal landing page for hiddenden.cafe
 **Owner:** Latte (gay furry developer, values self-hosting and privacy)
-**Tech Stack:** Astro 4.x, TypeScript, Vanilla CSS, Docker + Nginx
+**Tech Stack:** Astro 4.x (hybrid SSR), TypeScript, Vanilla CSS, SQLite, Docker + Node.js
 **Aesthetic:** Warm coffee/cappuccino theme, cozy hidden den vibes
 **Deployment:** Docker containers pushed to Gitea registry at git.hiddenden.cafe
 
@@ -40,14 +40,17 @@ cozy-den/
 
 ## Architecture Notes
 
-This is a simple static site following standard Astro conventions:
+Astro **hybrid SSR** site — most pages are statically pre-rendered, but guestbook and admin pages are server-rendered:
 - Layouts in `src/layouts/` for reusable page templates
 - Pages in `src/pages/` (routes automatically based on filename)
-- All content is on a single page (`index.astro`) with multiple sections
-- Custom 404 page with cozy theming
-- No client-side JavaScript - pure static HTML/CSS output
+- Server-side lib code in `src/lib/` (db, auth, guestbook, webauthn, spam)
+- API routes in `src/pages/api/` for form handling, WebAuthn, and admin actions
 - CSS custom properties centralized in `BaseLayout.astro` for theming
-- Accessibility improvements with ARIA labels and semantic HTML
+- `output: 'hybrid'` + `@astrojs/node` adapter — Node.js standalone server in production
+- SQLite database (better-sqlite3) for guestbook entries, sessions, and credentials
+- Docker runtime is now Node.js (not Nginx); see `docs/guestbook.md` for setup
+
+**Guestbook:** See `docs/guestbook.md` for full setup, YubiKey registration, and deployment notes.
 
 ## Commands