feat: add 6 more skins (PS1, PS3, Wii, NDS, Dreamcast, JV2002)

Brings the catalog to nine. Each is a single scoped [data-theme="..."]
CSS file plus a registry entry — no markup changes.

- ps1: charcoal BIOS, gray panels, uppercase letterspacing
- ps3: animated XMB sky gradient + drifting wave, black glass
- wii: white channels, rounded pills, soft blue glow
- nds: silver shell with content framed as the touch screen
- dreamcast: cream BIOS, conic-gradient orange swirl, lowercase blue
- jv2002: dense boxy portal, Verdana 11px, red masthead, blue nav tabs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -18,6 +18,20 @@ Open [http://localhost:3000](http://localhost:3000) with your browser to see the
 
 You can start editing the page by modifying `app/page.tsx`. The page auto-updates as you edit the file.
 
+## Admin panel
+
+Visit [http://localhost:3000/admin](http://localhost:3000/admin) and sign in with
+`ADMIN_PASSWORD` (see `.env.example`; defaults to `admin` in dev). From there you can:
+
+- **Posts** — full create / edit / delete with Markdown bodies, slugs, tags, and dates.
+- **Settings** — branding (title, subtitle, footer, version), the default theme for
+  new visitors, whether the public theme switcher is shown, and which skins it offers.
+- **Import / export** — download a JSON backup of settings and/or posts, and import
+  one back (posts can replace or append).
+
+Auth is a single password kept in `ADMIN_PASSWORD`, with a signed session cookie
+(`ADMIN_SESSION_SECRET`). All `/admin/*` routes are gated by middleware.
+
 This project uses [`next/font`](https://nextjs.org/docs/app/building-your-application/optimizing/fonts) to automatically optimize and load [Geist](https://vercel.com/font), a new font family for Vercel.
 
 ## Learn More