feat: add deployment guide, nginx/systemd configs, switch to adapter-node

- Add docs/DEPLOYMENT.md: step-by-step Proxmox LXC guide (Debian 13,
  PostgreSQL, nginx reverse proxy, systemd services)
- Add nginx/innercontext.conf: proxy /api/ → uvicorn, /mcp/ → uvicorn
  with SSE streaming support, / → SvelteKit Node server
- Add systemd/innercontext.service and innercontext-node.service
- Switch frontend from adapter-auto to adapter-node (required for
  +page.server.ts form actions); install adapter-node 5.5.4
- Update README.md: add frontend, MCP sections; fix /skin-snapshots →
  /skincare; update repo layout
- Replace frontend/README.md generic Svelte template with project docs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/package.json

@@ -14,7 +14,7 @@
 	"devDependencies": {
 		"@internationalized/date": "^3.11.0",
 		"@lucide/svelte": "^0.561.0",
-		"@sveltejs/adapter-auto": "^7.0.0",
+		"@sveltejs/adapter-node": "^5.0.0",
 		"@sveltejs/kit": "^2.50.2",
 		"@sveltejs/vite-plugin-svelte": "^6.2.4",
 		"@tailwindcss/vite": "^4.2.1",