feat(spec): implement partition path generation

[QuakeWang]

Purpose

Linked issue: close #127

Brief change log

Tests

API and Format

Documentation

[luoyuxia]

@QuakeWang Thanks for the pr. Left minor comments. PTAL

[QuakeWang]

@QuakeWang Thanks for the pr. Left minor comments. PTAL

@luoyuxia Thanks for the review! All comments have been addressed in the latest commit:

1. Unified all BinaryRow get_* methods to return Result — no more try_get_* / panic duality.
2. Preserved Utf8Error source chain.
3. Introduced PartitionComputer struct with a separate generate_part_values method.
4. Float/Double partition keys now return Unsupported.
5. Extracted test helpers to reduce boilerplate.

PTAL, thanks!

[luoyuxia]

+1

[JingsongLi]

+1