fix: 移除未知事件格式的日志噪声 (#96)

问题：
- codeagent-wrapper 在处理 Claude Code 等其他后端的事件流时
- 对无法识别的事件格式（turn.started/assistant/user）打印警告日志
- 造成输出噪声，影响用户体验

修复：
- parser.go:274 - 移除对未知事件的 warnFn 日志打印
- 改为静默 continue，直接跳过这些事件
- 添加注释说明这些事件来自其他后端，无需处理

测试：
- 新增 parser_unknown_event_test.go 回归测试
- 验证未知事件不产生 "Agent event:" 日志
- 确保 Codex/Claude/Gemini 事件解析不受影响
- 所有测试通过

Closes #96

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

codeagent-wrapper/parser.go

@@ -271,8 +271,8 @@ func parseJSONStreamInternal(r io.Reader, warnFn func(string), infoFn func(strin
 			continue
 		}
 
-		// Unknown event format
-		warnFn(fmt.Sprintf("Unknown event format: %s", truncateBytes(line, 100)))
+		// Unknown event format from other backends (turn.started/assistant/user); ignore.
+		continue
 	}
 
 	switch {

codeagent-wrapper/parser_unknown_event_test.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestBackendParseJSONStream_UnknownEventsAreSilent(t *testing.T) {
+	input := strings.Join([]string{
+		`{"type":"turn.started"}`,
+		`{"type":"assistant","text":"hi"}`,
+		`{"type":"user","text":"yo"}`,
+		`{"type":"item.completed","item":{"type":"agent_message","text":"ok"}}`,
+	}, "\n")
+
+	var infos []string
+	infoFn := func(msg string) { infos = append(infos, msg) }
+
+	message, threadID := parseJSONStreamInternal(strings.NewReader(input), nil, infoFn, nil, nil)
+	if message != "ok" {
+		t.Fatalf("message=%q, want %q (infos=%v)", message, "ok", infos)
+	}
+	if threadID != "" {
+		t.Fatalf("threadID=%q, want empty (infos=%v)", threadID, infos)
+	}
+
+	for _, msg := range infos {
+		if strings.Contains(msg, "Agent event:") {
+			t.Fatalf("unexpected log for unknown event: %q", msg)
+		}
+	}
+}
+