vLLM 도구 호출 스트리밍 실행기와 코워크 루프 실시간 소비 구조 추가

- LlmService에 tool-use 전용 streaming event API를 추가하고 OpenAI vLLM IBM 경로의 partial tool_call 조립을 event 기반으로 재구성함
- Cowork/Code 루프가 streaming event를 직접 소비하도록 바꿔 도구 호출 감지와 진행 표시를 더 빠르게 갱신함
- read-only 도구 조기 실행이 기존 loop와 실제로 이어지도록 정리하고 최종 실행에서는 prefetch 결과를 재사용함
- README와 DEVELOPMENT 문서를 2026-04-08 11:31(KST) 기준으로 갱신함

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/Agent/AgentLoopService.cs

@@ -2,6 +2,7 @@
 using System.Diagnostics;
 using System.Collections.Concurrent;
 using System.IO;
+using System.Text;
 using System.Text.Json;
 using AxCopilot.Models;
 using AxCopilot.Services;
@@ -548,6 +549,8 @@ public partial class AgentLoopService
                     var (_, currentModel) = _llm.GetCurrentModelInfo();
                     WorkflowLogService.LogLlmRequest(_conversationId, _currentRunId, iteration,
                         currentModel, sendMessages.Count, activeTools.Count, forceFirst);
+                    var streamedTextPreview = new StringBuilder();
+                    var lastStreamUiUpdateAt = DateTime.MinValue;
 
                     blocks = await SendWithToolsWithRecoveryAsync(
                         sendMessages,
@@ -560,7 +563,39 @@ public partial class AgentLoopService
                             block,
                             activeTools,
                             context,
-                            ct));
+                            ct),
+                        onStreamEventAsync: async evt =>
+                        {
+                            switch (evt.Kind)
+                            {
+                                case LlmService.ToolStreamEventKind.TextDelta:
+                                    if (!string.IsNullOrWhiteSpace(evt.Text))
+                                    {
+                                        streamedTextPreview.Append(evt.Text);
+                                        var now = DateTime.UtcNow;
+                                        if ((now - lastStreamUiUpdateAt).TotalMilliseconds >= 450 && streamedTextPreview.Length > 0)
+                                        {
+                                            var preview = streamedTextPreview.ToString();
+                                            preview = preview.Length > 140 ? preview[..140] + "…" : preview;
+                                            EmitEvent(AgentEventType.Thinking, "", preview);
+                                            lastStreamUiUpdateAt = now;
+                                        }
+                                    }
+                                    break;
+                                case LlmService.ToolStreamEventKind.ToolCallReady:
+                                    if (evt.ToolCall != null)
+                                    {
+                                        EmitEvent(
+                                            AgentEventType.Thinking,
+                                            evt.ToolCall.ToolName,
+                                            $"스트리밍 도구 감지: {FormatToolCallSummary(evt.ToolCall)}");
+                                    }
+                                    break;
+                                case LlmService.ToolStreamEventKind.Completed:
+                                    await Task.CompletedTask;
+                                    break;
+                            }
+                        });
                     runState.ContextRecoveryAttempts = 0;
                     llmCallSw.Stop();
                     runState.TransientLlmErrorRetries = 0;