feat: add geospatial parquet write support [3/3]

[wirybeaver]

Summary

Part 3 of the geospatial support stack. Depends on #3341 and #2933.

• Writes Arrow WKB extension fields as Parquet geometry/geography logical types.
• Preserves CRS and geography edge-interpolation metadata.
• Omits optional scalar lower/upper bounds until geospatial zonemap statistics are implemented.
• Adds an end-to-end Iceberg writer/reader round trip that verifies WKB payloads and Parquet logical metadata.

For the review-only delta over part 2: wirybeaver/iceberg-rust@support-geometry-geography-read...support-geometry-geography-write

Tests

• cargo check -p iceberg --locked
• cargo test -p iceberg geospatial
• cargo test -p iceberg avro_bytes_geometry