fix(scan): prune primary-key files with key stats

[QuakeWang]

Purpose

Rust key-value files store primary-key statistics in key_stats, while scan pruning only evaluated value_stats. As a result, Rust-written primary-key files with empty value stats could not be pruned by primary-key predicates.

Brief change log

• Evaluate file-safe primary-key predicates against key_stats.
• Resolve key-stat layouts using trimmed primary-key order across schema evolution.
• Preserve fail-open behavior for missing or invalid statistics.
• Add regression tests for Rust-written files, composite keys, schema evolution, and corrupted stats.

Tests

• cargo fmt --all -- --check
• cargo clippy --locked --all-targets --workspace --features fulltext,vortex -- -D warnings
• cargo test --locked -p paimon --all-targets --features fulltext,vortex
• cargo test --locked -p paimon-rest-server --all-targets

API and Format

Documentation

[XiaoHongbo-Hope]

+1