fix(squad): stop requiring fields.json as hard PI runner target

Organizer still prompts for fields.json, but missing it must not fail
closed as MISSING_TARGET when output.md is present (FullNone flake).

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/squad/workflow.go

@@ -466,9 +466,9 @@ func (d *WorkflowDriver) runOneStep(
 	agentsData, _ := os.ReadFile(filepath.Join(subDir, "AGENTS.md"))
 
 	targets := []string{deliverableName}
-	if step.Role == "organizer" {
-		targets = append(targets, "fields.json")
-	}
+	// fields.json is requested in TASK.md for organizer, but must not be a hard
+	// runner target: models often emit only output.md when materials are thin,
+	// and that used to fail closed as MISSING_TARGET / kill FullNone nightly.
 
 	// 治理：执行前重复识别——若历史轨迹显示该步骤已连续两次无进度重复，强制终止
 	if mu != nil {