Function rows_to_record_batch 

pub fn rows_to_record_batch(rows: &[Row]) -> Result<RecordBatch, ChartError>

Convert Vec<Row> into an Arrow RecordBatch.

Type inference strategy:

• Numbers → Float64
• Booleans → Boolean
• Strings → Utf8
• Null → nullable (skipped during inference)
• Mixed types → coerced to Utf8