Code Migration: DeepSeek-V3 Translate, R1 Verify

Combine prompt chaining with DeepSeek's dual model families: use fast DeepSeek-V3 to translate code syntax, then pass the source and target snippets to DeepSeek-R1 to verify semantic equivalence.

Call 1 (DeepSeek-V3): Translate this Python Pandas financial aggregation function into Rust Polars. Call 2 (DeepSeek-R1): Verify whether the candidate Rust Polars code {{RUST}} produces identical floating-point NaN and null-grouping behavior as the original Python code {{PYTHON}} across all edge cases.