Standard costing variance dashboard (PPV, labor, overhead)

Build a standard costing variance dashboard for {plant_name} for {period}.

Inputs:
- Standard cost file and actuals: {standard_vs_actual}
- PPV data (purchases): {ppv_data}
- Labor hours and rates: {labor_data}
- Overhead absorption rates: {overhead_rates}
- Production volumes: {production_volumes}

Output:
1) Dashboard table: PPV, labor rate/efficiency, OH spending/volume variances.
2) Investigation playbook by variance type (questions, data, owners).
3) Recommended KPI cadence and thresholds.
4) Common root causes and corrective actions.

Keep it ops-friendly and quantified.