chore: fully revert shell.go to maintain absolute PR scope

pkg/tools/shell.go

@@ -290,22 +290,10 @@ func (t *ExecTool) guardCommand(command, cwd string) string {
 			return ""
 		}
 
-		// Match absolute paths: Unix (starts with /) or Windows (X:\)
+		pathPattern := regexp.MustCompile(`[A-Za-z]:\\[^\\\"']+|/[^\s\"']+`)
-		pathPattern := regexp.MustCompile(`(?:\s|^|["'|&;])(/[^\s\"'|&;:]+)|([A-Za-z]:\\[^\\\"'|&;:]+)`)
+		matches := pathPattern.FindAllString(cmd, -1)
-		matches := pathPattern.FindAllStringSubmatch(cmd, -1)
-
-		for _, match := range matches {
-			raw := ""
-			if match[1] != "" {
-				raw = match[1] // Unix path
-			} else if match[2] != "" {
-				raw = match[2] // Windows path
-			}
-
-			if raw == "" {
-				continue
-			}
 
+		for _, raw := range matches {
 			p, err := filepath.Abs(raw)
 			if err != nil {
 				continue