Add multi-page router with mobile-responsive nav

- Install svelte-spa-router for hash-based client-side routing
- Extract Nav component with hamburger menu [ MENU ]/[ CLOSE ] for mobile
- Add pages: Home, Augmentum, Visage, MrHaven, Ecosystem
- Refactor App.svelte as router shell with shared footer
- All pages use consistent dark→white→dark→white section rhythm
- Mobile responsive: single-column layouts, fixed overlay mobile menu

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

Author: ccross2

package-lock.json

@@ -12,5 +12,9 @@
     "@sveltejs/vite-plugin-svelte": "^6.2.1",
     "svelte": "^5.45.2",
     "vite": "^7.3.1"
+  },
+  "dependencies": {
+    "geist": "^1.7.0",
+    "svelte-spa-router": "^4.0.1"
   }
 }