feat(branding): validate URL constants on module init (F11.2)

BrandingLinks (5 Hellion-owned URLs) and IntegrationLinks (2 third-party
plugin URLs) now run through UrlValidation.ValidateAll from a
[ModuleInitializer] hook. A malformed URL throws InvalidOperationException
at plugin load with the source class and the broken URL in the message,
instead of silently failing when a user clicks the button.

CA2255 is suppressed at the attribute sites — the warning is for library
code shipped to unknown consumers, but the plugin DLL is loaded directly
by Dalamud, which makes module-init the right one-shot hook.

HellionChat/Integrations/IntegrationLinks.cs

@@ -1,3 +1,6 @@
+using System.Runtime.CompilerServices;
+using HellionChat.Util;
+
 namespace HellionChat.Integrations;
 
 // Third-party plugin URLs — separate from BrandingLinks (Hellion-owned URLs).
@@ -5,4 +8,13 @@ internal static class IntegrationLinks
 {
     public const string HonorificRepo = "https://github.com/Caraxi/Honorific";
     public const string HonorificAuthor = "https://github.com/Caraxi";
+
+    // See BrandingLinks.ValidateUrls for the CA2255 rationale.
+#pragma warning disable CA2255
+    [ModuleInitializer]
+#pragma warning restore CA2255
+    internal static void ValidateUrls()
+    {
+        UrlValidation.ValidateAll(nameof(IntegrationLinks), HonorificRepo, HonorificAuthor);
+    }
 }