P1-5: upgrade polars 0.38 to current

[trial123Zel]

Roadmap task

P1-5

Problem

polars is pinned at 0.38.3 and must be upgraded to the current release. This touches the schema/series API throughout cryo_freeze, including a with_series! -> with_column rename.

Affected files

• crates/freeze/src/types/dataframes/ and dataset files using the polars series API
• crates/to_df/

Acceptance criteria

• The workspace builds against current polars.
• All Parquet output is schema-identical to the P1-0 baseline.

Validation method

cargo build + cryo_test all-datatype diff vs the P1-0 baseline.

References & credit

ROADMAP P1-5. Intertwined with P1-1..P1-4. Reference: upstream PR paradigmxyz#244 (@clouds56).

[trial123Zel]

Completed in Phase 1 PR #63 (merged as 72d5f62). Auto-close missed this issue — GitHub's Closes #a, #b syntax only closes the first number, so closing manually.