컨텍스트 압축 계층 확장과 세션 누적 계측 보강

- claude-code compact 흐름을 참고해 AX에 session memory compact, microcompact, collapse/snip 단계를 추가하고 ContextCondenser를 단계별 결과 반환 구조로 확장함

- ChatConversation과 AX Agent 하단 컨텍스트 카드에 대화별 compact 누적 회수, 절감 토큰, session memory/microcompact/snip 집계를 반영함

- AGENTS.md에 개발 단계부터 최적화와 실행 속도를 우선 고려하는 작업 지침을 추가함

- 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/Models/ChatModels.cs

@@ -139,6 +139,42 @@ public class ChatConversation
 
     [JsonPropertyName("conversationSortMode")]
     public string ConversationSortMode { get; set; } = "activity";
+
+    [JsonPropertyName("compactionCount")]
+    public int CompactionCount { get; set; }
+
+    [JsonPropertyName("automaticCompactionCount")]
+    public int AutomaticCompactionCount { get; set; }
+
+    [JsonPropertyName("manualCompactionCount")]
+    public int ManualCompactionCount { get; set; }
+
+    [JsonPropertyName("compactionSavedTokens")]
+    public int CompactionSavedTokens { get; set; }
+
+    [JsonPropertyName("sessionMemoryCompactionCount")]
+    public int SessionMemoryCompactionCount { get; set; }
+
+    [JsonPropertyName("microcompactBoundaryCount")]
+    public int MicrocompactBoundaryCount { get; set; }
+
+    [JsonPropertyName("snipCompactionCount")]
+    public int SnipCompactionCount { get; set; }
+
+    [JsonPropertyName("lastCompactionAt")]
+    public DateTime? LastCompactionAt { get; set; }
+
+    [JsonPropertyName("lastCompactionWasAutomatic")]
+    public bool LastCompactionWasAutomatic { get; set; }
+
+    [JsonPropertyName("lastCompactionBeforeTokens")]
+    public int? LastCompactionBeforeTokens { get; set; }
+
+    [JsonPropertyName("lastCompactionAfterTokens")]
+    public int? LastCompactionAfterTokens { get; set; }
+
+    [JsonPropertyName("lastCompactionStageSummary")]
+    public string? LastCompactionStageSummary { get; set; }
 }
 
 public class ChatAgentRunRecord