feat: initialize VPS fleet manager with server management functionality

- Add package.json for project metadata and dependencies
- Create server.js for API endpoints and server logic
- Implement data persistence using JSON file for server information
- Add HTML frontend (vps_manager.html) for server management interface
- Include Leaflet for map visualization of server locations
- Create start.bat for easy server startup on Windows

.wolf/cerebrum.md

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+# Cerebrum: vps-manager
+
+## Preferences
+- Keep all UI in a single HTML file (no build step, no framework)
+- Dark GitHub-style theme must be preserved exactly
+- IBM Plex Mono / IBM Plex Sans fonts
+
+## Do-Not-Repeat
+- Do NOT use window.storage (non-standard, breaks in browser) — use fetch + REST API
+- Do NOT split HTML/CSS/JS into separate files unless user asks