Function infer_schema 

pub fn infer_schema(path: &Path) -> Result<Schema, SchemaInferError>

Infer the Arrow schema from a data file by extension.

Dispatches to the appropriate reader based on file extension:

• .csv → CSV header + sample inference
• .json / .ndjson → JSON schema inference
• .parquet → Parquet footer metadata

Only reads the minimum data needed (header/sample rows/footer), not the full file.