feat(explore): feature Lotus Guild Space + favorite rooms, add matrixrooms.info directory

Populates the previously-empty featuredCommunities block so the Explore
tab's Featured page shows the Lotus Guild Space and a few community
favorites by default, and adds matrixrooms.info as a browsable server
in the Explore sidebar (it speaks enough of the Matrix federation API
to serve as an aggregated public-room search across the network).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

config.json

@@ -4,9 +4,9 @@
   "allowCustomHomeservers": true,
   "featuredCommunities": {
     "openAsDefault": false,
-    "spaces": [],
+    "spaces": ["!-1ZBnAH-JiCOV8MGSKN77zDGTuI3pgSdy8Unu_DrDyc"],
-    "rooms": [],
+    "rooms": ["#jellyfin:matrix.org", "#homelabbing:codestorm.net", "#proxmox:codestorm.net"],
-    "servers": []
+    "servers": ["matrixrooms.info"]
   },
   "hashRouter": {
     "enabled": false,