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.

.gitignore

@@ -1,10 +1,5 @@
-# Nuxt dev/build outputs
-.output
-.data
-.nuxt
-.nitro
-.cache
-dist
+# Outline secrets
+outline.env
 
 # Node dependencies
 node_modules
@@ -33,6 +28,6 @@ conflict-files-obsidian-git.md
 .env.*
 !.env.example
 
-/*.md
-/migration/*
-MIGRATION_STATUS.txt
+# Project docs (local only)
+/docs
+/migration