feat: improve task runner environment configuration

- Remove Crawlab-specific environment variables from the task runner's environment
- Automatically create workspace directory if it doesn't exist
- Enhance environment setup to prevent potential configuration conflicts

core/task/handler/runner.go

@@ -390,6 +390,16 @@ func (r *Runner) configureEnv() {
 
 	// Default envs
 	r.cmd.Env = os.Environ()
+
+	// Remove CRAWLAB_ prefixed environment variables
+	for i := 0; i < len(r.cmd.Env); i++ {
+		if strings.HasPrefix(r.cmd.Env[i], "CRAWLAB_") {
+			r.cmd.Env = append(r.cmd.Env[:i], r.cmd.Env[i+1:]...)
+			i--
+		}
+	}
+
+	// Task-specific environment variables
 	r.cmd.Env = append(r.cmd.Env, "CRAWLAB_TASK_ID="+r.tid.Hex())
 
 	// Global environment variables