Configure via `cplace_resource_planner_configure_columns` tool.

**JSON Format** (stored as stringified JSON):
```json
{
  "columns": [
    {
      "feature": "cf.cplace.resourceManagement.startDate",
      "header": "Start Date",
      "builtin": true,
      "visible": true
    },
    {
      "feature": "cf.cplace.myApp.customAttribute",
      "header": "Custom Field",
      "builtin": false,
      "visible": false
    }
  ]
}
```

Each column entry requires all 4 fields:
- `feature`: Fully-qualified attribute name
- `header`: Display name shown in column header
- `builtin`: `true` for built-in columns, `false` for custom attribute columns
- `visible`: Whether the column is visible by default

Full replacement semantics — the provided array completely replaces the current configuration.
Use `cplace_resource_planner_get_configuration` to read current columns before modifying.