Integrate NDK for Nostr client functionality and update dependencies

This commit introduces the Nostr Development Kit (NDK) to enhance the Nostr client functionality. Key changes include:

- Added `NDKPrivateKeySigner` for improved authentication methods in `LoginModal.svelte` and `App.svelte`.
- Refactored the Nostr client to utilize NDK for connection and event fetching, streamlining the connection process and event handling.
- Updated `go.mod` and `package.json` to include `@nostr-dev-kit/ndk` as a dependency.
- Created a new `package-lock.json` to reflect the updated dependency tree.

These changes improve the overall architecture and maintainability of the Nostr client.

app/web/package.json

@@ -19,6 +19,7 @@
     "svelte": "^3.55.0"
   },
   "dependencies": {
+    "@nostr-dev-kit/ndk": "^2.17.3",
     "sirv-cli": "^2.0.0"
   }
 }