Phase 8: Patch - Refactor to Polars

[mattsan-dev]

Overview
The MapPhase step now produces data using Polars LazyFrames, but the PatchPhase step still uses the legacy implementation and cannot process this new output. To keep the pipeline consistent and efficient, the PatchPhase phase must be updated to use the Polars version. This will keep existing behaviour while modernising the underlying process.

Tech Approach

• Update digital_land/phase/PatchPhase.py so it delegates to the Polars PatchPhase implementation.
• Implement the full PatchPhase logic inside digital_land/phase_polars/transform/PatchPhase.py.
• Convert existing PatchPhase rules into Polars lazy transformations.
• Ensure the PatchPhase phase accepts the LazyFrame produced by the new PatchPhase step.
• Keep the same public interface so no downstream code needs changing.

Acceptance Criteria/Tests

• PatchPhase phase accepts the PatchPhase phase LazyFrame without errors.
• Legacy PatchPhase behaviour is reproduced using Polars.
• Outputs match the legacy PatchPhase phase (apart from expected improvements).
• No Pandas or row‑based Python operations are used.
• Add test cases
• Refactored code complies with project formatting and style standards (black/flake8/pep)

Resourcing & Dependencies
Depends on MapPhase, no external teams.

[lakshmi-kovvuri1]

Applying regex-based patches to field values using Polars LazyFrame.Testing in progress

[lakshmi-kovvuri1]

tested the path logic with negative and positive scenario, negative scenario record is filtered.

[lakshmi-kovvuri1]

@VENKAT-AVVARI-190825
Please add unit test cases for this one (tests/unit/phase_polars/transform/patch.py) please confirm that this is working and make any changes necessary.
Please also check that the refactored code complies with project formatting and style standards (black/flake8/pep) and make any necessary changes.