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/PayloadHandler.cs

@@ -131,7 +131,7 @@ public sealed class PayloadHandler
             }
             catch (Exception ex)
             {
-                Plugin.Log.Error(ex, "Error executing integration");
+                Plugin.LogProxy.Error(ex, "Error executing integration");
             }
         }
 
@@ -535,7 +535,7 @@ public sealed class PayloadHandler
             )
         )
         {
-            Plugin.Log.Warning("Could not find DalamudLinkHandlers");
+            Plugin.LogProxy.Warning("Could not find DalamudLinkHandlers");
             return;
         }
 
@@ -546,7 +546,7 @@ public sealed class PayloadHandler
         }
         catch (Exception ex)
         {
-            Plugin.Log.Error(ex, "Error executing DalamudLinkPayload handler");
+            Plugin.LogProxy.Error(ex, "Error executing DalamudLinkPayload handler");
         }
     }