[spoon-lz]

Purpose

Closes #4921.

Avoid decoding unrequested columns in remote Arrow logs for both row and batch scans, including historical-schema reads with projection.

Brief change log

• Pass source-column selections to the Arrow IPC decoder.
• Remap historical-schema alignment while preserving missing-column nulls, output order, duplicates, and row counts.
• Keep full-column and server-projected decoding paths unchanged.

Remote download size is unchanged. No nested leaf pruning is introduced.

Tests

• Cover NONE, LZ4, and ZSTD; nested columns; reordered and duplicate selections; empty batches; and missing historical columns.
• Exercise public row and batch poll paths with file-backed historical logs in both schema modes.
• Verify that unselected compressed columns are not decompressed.
• Rust workspace tests, 914 core unit tests, Clippy, and formatting checks passed locally.

Live-cluster integration tests were not run.

API and Format

No public API, configuration, RPC, or storage-format changes.

Documentation

Updated the affected code comment. No new user-facing configuration.

Generative AI disclosure

Generative AI tools used: OpenAI Codex (GPT-6).
Generated-by: OpenAI Codex (GPT-6).