Fix Filter v2 integration semantics

[rustyconover]

Bring the Rust Filter v2 helpers/evaluator into parity with the canonical integration suite:

• compare dictionary columns using their logical value type
• derive discrete values through conjunctions and complete disjunctions
• derive normalized integer bounds from comparisons, IN sets, AND, and OR
• render exact IN members and Python-compatible diagnostic filter reprs
• refresh split and late-materialization witnesses for dynamic filters

Validated on ARM64 EC2 with a matching source-built VGI extension:

• cargo fmt --all -- --check
• cargo clippy -p vgi --all-targets --all-features -- -D warnings
• cargo test -p vgi --all-features (85 unit + 5 split-token + 4 doc tests passed)
• workspace build with all features
• Python canonical Filter v2 runner (29/29 cases)
• full stdio integration lane (309 cases, 11,337 assertions; all passed)
• focused split dynamic-filter and late-materialization tests (72 assertions; all passed)

Launch/HTTP full-lane validation is continuing on the same matching artifact and will be reported separately.