Phase 2: Extract IPluginLogger and KillTracker

- Create IPluginLogger interface, PluginCore implements it
- CharacterStats.cs and WebSocket.cs now use IPluginLogger instead of PluginCore.WriteToChat
- Extract KillTracker.cs: owns kill detection (all 36 regex patterns), death tracking,
  rate calculation, and the 1-sec stats update timer
- Bridge properties on PluginCore maintain backward compat for WebSocket telemetry

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

MosswartMassacre/CharacterStats.cs

@@ -26,6 +26,8 @@ namespace MosswartMassacre
 
     public static class CharacterStats
     {
+        private static IPluginLogger _logger;
+
         // Cached allegiance data (populated from network messages)
         private static string allegianceName;
         private static int allegianceSize;
@@ -44,8 +46,9 @@ namespace MosswartMassacre
         /// <summary>
         /// Reset all cached data. Call on plugin init.
         /// </summary>
-        internal static void Init()
+        internal static void Init(IPluginLogger logger = null)
         {
+            _logger = logger;
             allegianceName = null;
             allegianceSize = 0;
             followers = 0;
@@ -112,7 +115,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Allegiance processing error: {ex.Message}");
+                _logger?.Log($"[CharStats] Allegiance processing error: {ex.Message}");
             }
         }
 
@@ -142,7 +145,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Property processing error: {ex.Message}");
+                _logger?.Log($"[CharStats] Property processing error: {ex.Message}");
             }
         }
 
@@ -169,7 +172,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Int64 property update error: {ex.Message}");
+                _logger?.Log($"[CharStats] Int64 property update error: {ex.Message}");
             }
         }
 
@@ -186,7 +189,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Title processing error: {ex.Message}");
+                _logger?.Log($"[CharStats] Title processing error: {ex.Message}");
             }
         }
 
@@ -201,7 +204,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Set title error: {ex.Message}");
+                _logger?.Log($"[CharStats] Set title error: {ex.Message}");
             }
         }
 
@@ -329,7 +332,7 @@ namespace MosswartMassacre
             }
             catch (Exception ex)
             {
-                PluginCore.WriteToChat($"[CharStats] Error collecting stats: {ex.Message}");
+                _logger?.Log($"[CharStats] Error collecting stats: {ex.Message}");
             }
         }
     }