feat(nostr): Add Nostr relay connection and status management

- Integrate nostr-tools for Nostr relay connectivity
- Create NostrClient for managing relay connections
- Implement useNostr composable for reactive connection handling
- Add ConnectionStatus component to display relay connection state
- Configure environment variable for Nostr relay endpoints
- Update App.vue to manage Nostr connection lifecycle

package.json

@@ -10,13 +10,14 @@
     "analyze": "vite build --mode analyze"
   },
   "dependencies": {
-    "@vueuse/core": "^12.5.0",
     "@vueuse/components": "^12.5.0",
+    "@vueuse/core": "^12.5.0",
     "@vueuse/head": "^2.0.0",
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "fuse.js": "^7.0.0",
     "lucide-vue-next": "^0.474.0",
+    "nostr-tools": "^2.10.4",
     "pinia": "^2.3.1",
     "radix-vue": "^1.9.13",
     "tailwind-merge": "^2.6.0",