[ISSUE-153] Add blocking poll into python bindings

[fresh-borzoni]

Purpose

Linked issue: close #153

Add a poll() method to Python LogScanner for incremental, timeout-based record reading.

Brief change log

• Add LogScanner.poll(timeout_ms) method to Python bindings
• Implement input validation for timeout parameter (rejects negative values)
• Return empty PyArrow table (with correct schema) on timeout instead of error
• Add example usage demonstrating poll-based consumption pattern

API and Format

• New public API: LogScanner.poll(timeout_ms: int) -> pyarrow.Table
• No storage format changes

[Copilot]

Pull request overview

This PR adds a poll() method to the Python LogScanner bindings, enabling incremental, timeout-based record reading with a configurable timeout parameter.

Changes:

• Added LogScanner.poll(timeout_ms) method with input validation and timeout handling
• Implemented create_empty_table() helper method to return properly-schemed empty tables on timeout
• Added example usage demonstrating the new poll-based consumption pattern

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
bindings/python/src/table.rs	Implements the new poll() method with validation, error handling, and empty table creation helper
bindings/python/example/example.py	Adds example demonstrating usage of the new poll() method

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[luoyuxia]

@fresh-borzoni Thanks for the pr. Only one question. PTAL

[luoyuxia]

actually, I'm thinking can we use scanner#poll_batches directly

[fresh-borzoni]

makes sense, thank you!

[fresh-borzoni]

i need #211 to be merged, so that I can use offsets in to_arrow() and to_pandas()

[fresh-borzoni]

@luoyuxia thanks for the review. Addressed comment.

I updated to use new poll_batches everywhere, since it's more efficient and we avoid conversions when we don't need them. Also added missing slicing to to_arrow

PTAL 🙏