The checks engine, the path and the cards: me-web? 0.1 reads the connection

MeWeb.Core runs seven checks concurrently and reports each as it settles:
online or behind a login page, this connection, the public IPv4 and IPv6
seen from v4./v6.meweb, the provider from a built-in map, the router
(UPnP IGD, NAT-PMP and PCP, read-only), address sharing (router WAN
against the echo, TTL hops only as a hint), and the history kept on the
device. The app draws the path from this device to the internet and lights
it node by node, with a card per check and a sheet listing every host it
contacts.

The provider map is iptoasn's table compressed to 2.1 MB by
tools/knowledge.cs and built before every app release; eleven Italian
provider profiles carry each fact with who said it, the source and the
month. The server gains a download page (en, it) and /download/{platform}
from the latest Gitea release.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

src/MeWeb.App/Services/Localizer.cs

@@ -27,7 +27,17 @@ public sealed class Localizer : INotifyPropertyChanged
 
   public string this[string key] => current.GetValueOrDefault(key) ?? english.GetValueOrDefault(key) ?? key;
 
-  public string Format(string key, params object[] args) => string.Format(Culture, this[key], args);
+  public string Format(string key, params object[] args)
+  {
+    try
+    {
+      return string.Format(Culture, this[key], args);
+    }
+    catch (FormatException)
+    {
+      return this[key];
+    }
+  }
 
   public void SetLanguage(Language language)
   {