📝 docs: add Astro Starlight public documentation site

Add comprehensive documentation site using Astro Starlight with:
- Getting Started guides (introduction, quick-start, project structure)
- Development docs (local dev, env vars, docker, migrations, testing)
- Architecture docs (overview, auth, backend, web, mobile, storage, search)
- Guidelines (code style, error handling, database, design/UX)
- Deployment docs (overview, Cloudflare Pages, Mac Mini, self-hosting)
- Project pages (overview, chat)
- API reference structure

Features:
- Dark mode support
- Full-text search (Pagefind)
- Tailwind CSS styling
- Cloudflare Pages deployment ready
- Edit on GitHub links

apps/docs/package.json

@@ -0,0 +1,28 @@
+{
+	"name": "@manacore/docs",
+	"version": "1.0.0",
+	"private": true,
+	"type": "module",
+	"scripts": {
+		"dev": "astro dev",
+		"start": "astro dev",
+		"build": "astro check && astro build",
+		"preview": "astro preview",
+		"astro": "astro",
+		"type-check": "astro check"
+	},
+	"dependencies": {
+		"@astrojs/check": "^0.9.0",
+		"@astrojs/sitemap": "^3.2.1",
+		"@astrojs/starlight": "^0.32.0",
+		"astro": "^5.16.0",
+		"sharp": "^0.33.0",
+		"typescript": "^5.0.0"
+	},
+	"devDependencies": {
+		"@astrojs/starlight-tailwind": "^3.0.0",
+		"@astrojs/tailwind": "^6.0.0",
+		"@tailwindcss/typography": "^0.5.16",
+		"tailwindcss": "^3.4.17"
+	}
+}