Replace Nuxt wiki with Outline deployment config

Strip the Nuxt 4 static site and replace with Docker Compose config
for self-hosted Outline wiki (Outline + PostgreSQL 16 + Redis 7).
Adds nginx reverse proxy with WebSocket support and CSS injection,
migration script for existing markdown articles, backup script,
and starter theme CSS.

scripts/package.json

@@ -0,0 +1,7 @@
+{
+  "private": true,
+  "type": "module",
+  "dependencies": {
+    "gray-matter": "^4.0.3"
+  }
+}