Add Kestrel's Hall to the featured sidebar links

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

config.toml

@@ -121,4 +121,9 @@ theme = "m10c"
     identifier = "bggpipe"
     name = "bggpipe: My automated boardgame organizer"
     url = "https://git.kestrelsnest.social/eric/bggpipe"
-    weight = 2
+    weight = 2
+  [[menu.featured]]
+    identifier = "gamehall"
+    name = "Kestrel's Hall: Play boardgames online with friends"
+    url = "https://gamehall.kestrelsnest.social/"
+    weight = 3