refactor(services): route logging through IPluginLogProxy

F12.2 step 5b — service cluster (~42 sites in 16 files):
MessageManager, GameFunctions/{Chat, GameFunctions, KeybindManager},
EmoteCache, PayloadHandler, AutoTellTabsService, FontManager, Commands,
Util/{WrapperUtil, AutoTranslate, MemoryUtil}, Message, Themes/ThemeRegistry,
Ipc/ExtraChat, Configuration.

The proxy interface gained Dalamud's params-overload signature
(messageTemplate + params object[]) to cover Configuration.cs:86 which
relies on Serilog-style placeholders.

Verified: zero remaining Plugin.Log.X(...) call-sites in HellionChat/,
build green, build-suite 690/690.

HellionChat/Commands.cs

@@ -52,7 +52,7 @@ internal sealed class Commands : IDisposable
     {
         if (!Registered.TryGetValue(command, out var wrapper))
         {
-            Plugin.Log.Warning($"Missing registration for command {command}");
+            Plugin.LogProxy.Warning($"Missing registration for command {command}");
             return;
         }
 
@@ -62,7 +62,7 @@ internal sealed class Commands : IDisposable
         }
         catch (Exception ex)
         {
-            Plugin.Log.Error(ex, $"Error while executing command {command}");
+            Plugin.LogProxy.Error(ex, $"Error while executing command {command}");
         }
     }
 }