fix(parallel): 修复并行执行启动横幅重复打印问题

修复 GitHub Actions 失败的测试 TestRunParallelStartupLogsPrinted。

问题根源：
- 在 main.go 中有重复的启动横幅和日志路径打印逻辑
- executeConcurrent 内部也添加了相同的打印逻辑
- 导致横幅和任务日志被打印两次

修复内容：
1. 删除 main.go 中 --parallel 处理中的重复打印代码（行 184-194）
2. 保留 executeConcurrent 中的 printTaskStart 函数，实现：
   - 在任务启动时立即打印日志路径
   - 使用 mutex 保护并发打印，确保横幅只打印一次
   - 按实际执行顺序打印任务信息

测试结果：
- TestRunParallelStartupLogsPrinted: PASS
- TestRunNonParallelOutputsIncludeLogPathsIntegration: PASS
- TestRunStartupCleanupRemovesOrphansEndToEnd: PASS

影响范围：
- 修复了 --parallel 模式下的日志输出格式
- 不影响非并行模式的执行

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

codeagent-wrapper/wrapper_name.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	defaultWrapperName = "codeagent-wrapper"
+	legacyWrapperName  = "codex-wrapper"
+)
+
+// currentWrapperName resolves the wrapper name based on the invoked binary.
+// Only known names are honored to avoid leaking build/test binary names into logs.
+func currentWrapperName() string {
+	if len(os.Args) == 0 {
+		return defaultWrapperName
+	}
+
+	base := filepath.Base(os.Args[0])
+	base = strings.TrimSuffix(base, ".exe") // tolerate Windows executables
+
+	switch base {
+	case defaultWrapperName, legacyWrapperName:
+		return base
+	default:
+		return defaultWrapperName
+	}
+}
+
+// logPrefixes returns the set of accepted log name prefixes, including the
+// current wrapper name and legacy aliases.
+func logPrefixes() []string {
+	prefixes := []string{currentWrapperName(), defaultWrapperName, legacyWrapperName}
+	seen := make(map[string]struct{}, len(prefixes))
+	var unique []string
+	for _, prefix := range prefixes {
+		if prefix == "" {
+			continue
+		}
+		if _, ok := seen[prefix]; ok {
+			continue
+		}
+		seen[prefix] = struct{}{}
+		unique = append(unique, prefix)
+	}
+	return unique
+}
+
+// primaryLogPrefix returns the preferred filename prefix for log files.
+// Defaults to the current wrapper name when available, otherwise falls back
+// to the canonical default name.
+func primaryLogPrefix() string {
+	prefixes := logPrefixes()
+	if len(prefixes) == 0 {
+		return defaultWrapperName
+	}
+	return prefixes[0]
+}