fix: set config.json to matrix.lotusguild.org by default

Remove upstream Cinny homeserver list and set Lotus Guild homeserver
as the only default. Prevents deploying with wrong homeserver on fresh builds.

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

public/config.json

@@ -0,0 +1,17 @@
+{
+  "defaultHomeserver": 0,
+  "homeserverList": [
+    "matrix.lotusguild.org"
+  ],
+  "allowCustomHomeservers": false,
+  "featuredCommunities": {
+    "openAsDefault": false,
+    "spaces": [],
+    "rooms": [],
+    "servers": []
+  },
+  "hashRouter": {
+    "enabled": false,
+    "basename": "/"
+  }
+}