Introduce FSST Support for Parquet

### Describe the enhancement requested

Tracks the support for FSST for byte array in Parquet format
Proposal: https://docs.google.com/document/d/1g7zgopxeHc5nofJXfc8EEp_HGMaI8g-jFVvNCs2GVA0/edit?tab=t.0#heading=h.2eyxl5kkyzy7

Start by reading the linked FSST proposal and the Parquet format specification to understand the requested byte-array support. The issue names no implementation files or tests, so identify the relevant format definitions and compatibility requirements before planning work. Done means the Parquet format explicitly supports FSST for byte arrays with accompanying validation or specification coverage.

Written by the indexing model from the issue text.