모델별 compact 사용량 계측과 압축 경계 UI 보강

- claw-code compaction accounting 흐름을 참고해 service:model 기준 일별 토큰 집계와 compact 이후 모델 사용량 버킷을 추가함

- microcompact/session_memory/collapsed boundary 메시지를 전용 압축 카드로 렌더링하고 compact 관련 thinking 이벤트를 얇은 compact pill로 분리함

- README 및 docs/DEVELOPMENT.md에 2026-04-05 00:01 (KST) 기준 이력을 반영함

- 검증: dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ (경고 0 / 오류 0)

src/AxCopilot/Services/UsageStatisticsService.cs

@@ -70,7 +70,7 @@ internal static class UsageStatisticsService
     }
 
     /// <summary>토큰 사용량을 기록합니다.</summary>
-    public static void RecordTokens(int promptTokens, int completionTokens)
+    public static void RecordTokens(int promptTokens, int completionTokens, string? service = null, string? model = null, bool isPostCompaction = false)
     {
         if (promptTokens <= 0 && completionTokens <= 0) return;
         EnsureInitialized();
@@ -79,6 +79,23 @@ internal static class UsageStatisticsService
             _today.PromptTokens += promptTokens;
             _today.CompletionTokens += completionTokens;
             _today.TotalTokens += promptTokens + completionTokens;
+
+            var key = BuildModelUsageKey(service, model);
+            if (!string.IsNullOrWhiteSpace(key))
+            {
+                _today.ModelPromptTokens.TryGetValue(key, out var modelPrompt);
+                _today.ModelCompletionTokens.TryGetValue(key, out var modelCompletion);
+                _today.ModelPromptTokens[key] = modelPrompt + promptTokens;
+                _today.ModelCompletionTokens[key] = modelCompletion + completionTokens;
+
+                if (isPostCompaction)
+                {
+                    _today.PostCompactionPromptTokens.TryGetValue(key, out var postPrompt);
+                    _today.PostCompactionCompletionTokens.TryGetValue(key, out var postCompletion);
+                    _today.PostCompactionPromptTokens[key] = postPrompt + promptTokens;
+                    _today.PostCompactionCompletionTokens[key] = postCompletion + completionTokens;
+                }
+            }
         }
         _ = SaveTodayAsync();
     }
@@ -205,8 +222,21 @@ internal static class UsageStatisticsService
         TotalTokens      = _today.TotalTokens,
         PromptTokens     = _today.PromptTokens,
         CompletionTokens = _today.CompletionTokens,
+        ModelPromptTokens = new Dictionary<string, long>(_today.ModelPromptTokens),
+        ModelCompletionTokens = new Dictionary<string, long>(_today.ModelCompletionTokens),
+        PostCompactionPromptTokens = new Dictionary<string, long>(_today.PostCompactionPromptTokens),
+        PostCompactionCompletionTokens = new Dictionary<string, long>(_today.PostCompactionCompletionTokens),
     };
 
     private static string GetFilePath(string dateStr)
         => Path.Combine(_statsDir, $"{dateStr}.json");
+
+    private static string BuildModelUsageKey(string? service, string? model)
+    {
+        var normalizedService = (service ?? "").Trim().ToLowerInvariant();
+        var normalizedModel = (model ?? "").Trim();
+        if (string.IsNullOrWhiteSpace(normalizedService) || string.IsNullOrWhiteSpace(normalizedModel))
+            return "";
+        return $"{normalizedService}:{normalizedModel}";
+    }
 }